Renovation Nightmare: Missed Drainage Pipe in Survey, now Flooding – Who’s Liable?

VintageJedi

This post is a bit long. There’s a short summary up front for the TL;DR crowd. The longer, detailed read is below, my questions at the end. Thanks.

Short Summary

We had an extension built. The project manager instructed a drainage survey before concrete was poured, but one of the main soil pipes—serving bathrooms and laundry—was never surveyed. That pipe is now likely collapsed beneath our new floor, causing flooding and rendering rooms unusable. The builder proceeded based on the incomplete survey, and the project manager either missed or ignored the omission.

The damage isn’t covered under the main policy with Aviva, but we do have legal expenses cover. Aviva referred us to Arc Legal, and I’m currently filing a claim. The case is complex, and it’s unclear whether liability lies with the project manager, the builder, or the drainage company.

Main Takeaways

1. The project manager advised us to hire a drainage company for a CCTV site survey. He chose the company; we paid.
2. The drainage company failed to survey one of the three soil pipes. No explanation provided.
3. The PM either didn’t read or didn’t notice the pipe was omitted from the report.
4. The builder poured concrete and built over the site without confirming full clearance. He now claims he trusted the PM’s word and never read the report.
5. Aviva says the damage isn’t covered under our home insurance policy—but legal expenses cover might apply.

---

Details

Background

In January 2024, we hired a building contractor and a project manager to oversee a whole house renovation and build an extension on our house. Our PM in April 2024 asked us to pay for a drainage company to do a CCTV site survey to make certain the drains were all clear before building over a public drain and pouring concrete. Our building contractor was onsite at the time at the time of the CCTV survey, our PM was not.

The Foul-up & Project Manager

Fast forward a year. We moved into the house at the end of April 2025. After about a week, water began coming up through the downstairs shower tray – and we had a minor flood. The water company did a CCTV survey – no problem on their end.   We asked the PM to see the original site survey report. He sent it and called us at the same time. Apparently, there are THREE waste pipes leading away from our house – and only TWO were surveyed.  He claims to not have known about it. Worth noting: the PM was generally incompetent, and my husband took over most of the project management. The PM effectively disappeared after we paid him in full. Lessons were learned.

The Drainage company

Mid-May 2025 - the original drainage company came to do another CCTV survey. We had to excavate our brand new flooring to access the third pipe. They couldn’t get the camera down the line—it appears completely blocked. They blasted gallons of water and blue-dyed water down the pipe, yet no trace of flow showed up in the manhole. No one knows where that water is going. This is unsettling news to me.

None of this appears in the report we received. When asked about it, they refused to discuss their correspondence with the project manager, citing GDPR rules. Then they sent us a bill for £754.

The Builder

That same evening, the building contractor came over and said he would fix it – great! He would need to dig up our floors down through to the concrete. He promised to get back to us in 2 weeks which was over 2 weeks ago.” He has a history of overpromising and running late (10 months over schedule, costing us over £10k in delays). We have little confidence he’ll return any time soon. I'm worried he could simply disappear on us.

Insurance and Legal cover

We didn’t have building insurance during the extension (don’t ask, I was unaware, it’s a touchy subject).  We bought an Aviva policy shortly before we moved back in. When the flooding occurred, they confirmed that underground pipes aren’t covered—but we do have legal expenses insurance.

Aviva Legal referred us to Arc Legal, who are now assessing whether our legal claim qualifies under the policy. However, because the original drainage survey occurred before the policy was active, they warned me it could be rejected. I’m still assembling documentation and submitting the claim.

Questions

• What are our next steps?

• Should we be looking for our own solicitor regardless of Arc Legal’s response?

• Are we now at risk for subsidence or structural damage from leaking or unconnected waste pipes? Or worse, our neighbours?

• Should we upgrade our insurance policy with better coverage for hidden damage, building work, or subsidence?

• What happens if additional issues (from the same build) are discovered in future -will we be covered under our current policy?

Emmia

I think the problem with future insurance is likely to be, that as a known issue it (and consequential/related issues) either won't be insurable or insurable at a reasonable cost.

DullGreyGuy

VintageJedi said:

This post is a bit long. There’s a short summary up front for the TL;DR crowd. The longer, detailed read is below, my questions at the end. Thanks.

Short Summary

We had an extension built. The project manager instructed a drainage survey before concrete was poured, but one of the main soil pipes—serving bathrooms and laundry—was never surveyed. That pipe is now likely collapsed beneath our new floor, causing flooding and rendering rooms unusable. The builder proceeded based on the incomplete survey, and the project manager either missed or ignored the omission.

The damage isn’t covered under the main policy with Aviva, but we do have legal expenses cover. Aviva referred us to Arc Legal, and I’m currently filing a claim. The case is complex, and it’s unclear whether liability lies with the project manager, the builder, or the drainage company.

Main Takeaways

• The project manager advised us to hire a drainage company for a CCTV site survey. He chose the company; we paid.
• The drainage company failed to survey one of the three soil pipes. No explanation provided.
• The PM either didn’t read or didn’t notice the pipe was omitted from the report.
• The builder poured concrete and built over the site without confirming full clearance. He now claims he trusted the PM’s word and never read the report.
• Aviva says the damage isn’t covered under our home insurance policy—but legal expenses cover might apply.

---

Details

Background

In January 2024, we hired a building contractor and a project manager to oversee a whole house renovation and build an extension on our house. Our PM in April 2024 asked us to pay for a drainage company to do a CCTV site survey to make certain the drains were all clear before building over a public drain and pouring concrete. Our building contractor was onsite at the time at the time of the CCTV survey, our PM was not.

The Foul-up & Project Manager

Fast forward a year. We moved into the house at the end of April 2025. After about a week, water began coming up through the downstairs shower tray – and we had a minor flood. The water company did a CCTV survey – no problem on their end.   We asked the PM to see the original site survey report. He sent it and called us at the same time. Apparently, there are THREE waste pipes leading away from our house – and only TWO were surveyed.  He claims to not have known about it. Worth noting: the PM was generally incompetent, and my husband took over most of the project management. The PM effectively disappeared after we paid him in full. Lessons were learned.

The Drainage company

Mid-May 2025 - the original drainage company came to do another CCTV survey. We had to excavate our brand new flooring to access the third pipe. They couldn’t get the camera down the line—it appears completely blocked. They blasted gallons of water and blue-dyed water down the pipe, yet no trace of flow showed up in the manhole. No one knows where that water is going. This is unsettling news to me.

None of this appears in the report we received. When asked about it, they refused to discuss their correspondence with the project manager, citing GDPR rules. Then they sent us a bill for £754.

The Builder

That same evening, the building contractor came over and said he would fix it – great! He would need to dig up our floors down through to the concrete. He promised to get back to us in 2 weeks which was over 2 weeks ago.” He has a history of overpromising and running late (10 months over schedule, costing us over £10k in delays). We have little confidence he’ll return any time soon. I'm worried he could simply disappear on us.

Insurance and Legal cover

We didn’t have building insurance during the extension (don’t ask, I was unaware, it’s a touchy subject).  We bought an Aviva policy shortly before we moved back in. When the flooding occurred, they confirmed that underground pipes aren’t covered—but we do have legal expenses insurance.

Aviva Legal referred us to Arc Legal, who are now assessing whether our legal claim qualifies under the policy. However, because the original drainage survey occurred before the policy was active, they warned me it could be rejected. I’m still assembling documentation and submitting the claim.

Questions

• What are our next steps?

1. Should we be looking for our own solicitor regardless of Arc Legal’s response?
2. Are we now at risk for subsidence or structural damage from leaking or unconnected waste pipes? Or worse, our neighbours?
3. Should we upgrade our insurance policy with better coverage for hidden damage, building work, or subsidence?
4. What happens if additional issues (from the same build) are discovered in future -will we be covered under our current policy?

1. If you engage your own solicitor now you may as well withdraw the Arc claim, your solicitor won't work under their terms and there is no need for two solicitors

2. Potentially but it depends on many factors 

3. You can't protect for defective workmanship on your home insurance, in principle were you able to then you could hire known cowboys for 10% of the real cost and then just get your insurers to pay for the real job to be done.

Home insurance however does cover a very valuable asset and the fact that sites like these promote price over value is concerning

4. Not if they are caused by defective workmanship


It seems unusual that you decided to hire a PM but then separately hire the main contractor; whilst this is common in my world of PMing in the insurance space my experience of construction is that the PM is supposed to create the single point of contract such that there isnt arguments over who's responsible for when things go wrong. For tax reasons they may ask that you settle bills directly with suppliers to try and avoid VAT registration but payment and contract are two seperate considerations. 

Going into the touchy subject, why didnt you have insurance? You literally didnt buy a policy or you did buy one but forgot to tell them about the building works and so it was invalidated or... ?

Grumpy_chap

VintageJedi said:

it’s unclear whether liability lies with the project manager, the builder, or the drainage company

Did you hire a separate (independent) PM outwith the builder construction company?

That is not common in domestic construction projects - individual householder schemes.  Why were the separate contracts let?

The drainage company will have surveyed the drains they were asked to survey.  If they were asked to camera two drains and there were three, the drainage company would only have surveyed the two drains they were asked to have surveyed.  The report may have referenced the other drain as present and not surveyed.  
What did the scope of works given to the drainage company specify?
What did the report say?

Who did the design?
Was the project design and build by the builder?
If the builder was aware of the drain, their construction techniques should have allowed for build over without damaging the drain regardless of the age / condition of the drain.

VintageJedi said:

 Our PM in April 2024 asked us to pay for a drainage company to do a CCTV site survey to make certain the drains were all clear before building over a public drain and pouring concrete. 

Were the drains surveyed public drains?  If so, was there a formal build over agreement in place?
Was the drain that was not surveyed and subsequently collapsed a public drain?

VintageJedi

DullGreyGuy said:

VintageJedi said:

This post is a bit long. There’s a short summary up front for the TL;DR crowd. The longer, detailed read is below, my questions at the end. Thanks.

Short Summary

We had an extension built. The project manager instructed a drainage survey before concrete was poured, but one of the main soil pipes—serving bathrooms and laundry—was never surveyed. That pipe is now likely collapsed beneath our new floor, causing flooding and rendering rooms unusable. The builder proceeded based on the incomplete survey, and the project manager either missed or ignored the omission.

The damage isn’t covered under the main policy with Aviva, but we do have legal expenses cover. Aviva referred us to Arc Legal, and I’m currently filing a claim. The case is complex, and it’s unclear whether liability lies with the project manager, the builder, or the drainage company.

Main Takeaways

• The project manager advised us to hire a drainage company for a CCTV site survey. He chose the company; we paid.
• The drainage company failed to survey one of the three soil pipes. No explanation provided.
• The PM either didn’t read or didn’t notice the pipe was omitted from the report.
• The builder poured concrete and built over the site without confirming full clearance. He now claims he trusted the PM’s word and never read the report.
• Aviva says the damage isn’t covered under our home insurance policy—but legal expenses cover might apply.

---

Details

Background

In January 2024, we hired a building contractor and a project manager to oversee a whole house renovation and build an extension on our house. Our PM in April 2024 asked us to pay for a drainage company to do a CCTV site survey to make certain the drains were all clear before building over a public drain and pouring concrete. Our building contractor was onsite at the time at the time of the CCTV survey, our PM was not.

The Foul-up & Project Manager

Fast forward a year. We moved into the house at the end of April 2025. After about a week, water began coming up through the downstairs shower tray – and we had a minor flood. The water company did a CCTV survey – no problem on their end.   We asked the PM to see the original site survey report. He sent it and called us at the same time. Apparently, there are THREE waste pipes leading away from our house – and only TWO were surveyed.  He claims to not have known about it. Worth noting: the PM was generally incompetent, and my husband took over most of the project management. The PM effectively disappeared after we paid him in full. Lessons were learned.

The Drainage company

Mid-May 2025 - the original drainage company came to do another CCTV survey. We had to excavate our brand new flooring to access the third pipe. They couldn’t get the camera down the line—it appears completely blocked. They blasted gallons of water and blue-dyed water down the pipe, yet no trace of flow showed up in the manhole. No one knows where that water is going. This is unsettling news to me.

None of this appears in the report we received. When asked about it, they refused to discuss their correspondence with the project manager, citing GDPR rules. Then they sent us a bill for £754.

The Builder

That same evening, the building contractor came over and said he would fix it – great! He would need to dig up our floors down through to the concrete. He promised to get back to us in 2 weeks which was over 2 weeks ago.” He has a history of overpromising and running late (10 months over schedule, costing us over £10k in delays). We have little confidence he’ll return any time soon. I'm worried he could simply disappear on us.

Insurance and Legal cover

We didn’t have building insurance during the extension (don’t ask, I was unaware, it’s a touchy subject).  We bought an Aviva policy shortly before we moved back in. When the flooding occurred, they confirmed that underground pipes aren’t covered—but we do have legal expenses insurance.

Aviva Legal referred us to Arc Legal, who are now assessing whether our legal claim qualifies under the policy. However, because the original drainage survey occurred before the policy was active, they warned me it could be rejected. I’m still assembling documentation and submitting the claim.

Questions

• What are our next steps?

1. Should we be looking for our own solicitor regardless of Arc Legal’s response?
2. Are we now at risk for subsidence or structural damage from leaking or unconnected waste pipes? Or worse, our neighbours?
3. Should we upgrade our insurance policy with better coverage for hidden damage, building work, or subsidence?
4. What happens if additional issues (from the same build) are discovered in future -will we be covered under our current policy?

1. If you engage your own solicitor now you may as well withdraw the Arc claim, your solicitor won't work under their terms and there is no need for two solicitors

2. Potentially but it depends on many factors 

3. You can't protect for defective workmanship on your home insurance, in principle were you able to then you could hire known cowboys for 10% of the real cost and then just get your insurers to pay for the real job to be done.

Home insurance however does cover a very valuable asset and the fact that sites like these promote price over value is concerning

4. Not if they are caused by defective workmanship


It seems unusual that you decided to hire a PM but then separately hire the main contractor; whilst this is common in my world of PMing in the insurance space my experience of construction is that the PM is supposed to create the single point of contract such that there isnt arguments over who's responsible for when things go wrong. For tax reasons they may ask that you settle bills directly with suppliers to try and avoid VAT registration but payment and contract are two seperate considerations. 

Going into the touchy subject, why didnt you have insurance? You literally didnt buy a policy or you did buy one but forgot to tell them about the building works and so it was invalidated or... ?

Our architect recommended the builder and then offered to take on the role as project manager. My husband was working 60+ hours/ week and I was working out of the country at the time so we needed a PM. He just turned out to be an absent and incompetent project manager. Our builder wasn't interested in managing the whole project -  only in the structural building. 

Right, I was out of the country and didn't know until 2 weeks ago that my partner had not renewed our policy and we didn't have insurance throughout the build. To say I was furious is an understatement. 

What do you know about Arc Legal? Why would Aviva deny our claim, yet potentially provide legal cover? I'm uninformed in the world of insurance, and I need to remedy that. 

VintageJedi

Grumpy_chap said:

VintageJedi said:

it’s unclear whether liability lies with the project manager, the builder, or the drainage company

Did you hire a separate (independent) PM outwith the builder construction company?

That is not common in domestic construction projects - individual householder schemes.  Why were the separate contracts let?

Who did the design?
Was the project design and build by the builder?
If the builder was aware of the drain, their construction techniques should have allowed for build over without damaging the drain regardless of the age / condition of the drain.

I just replied above to a similar comment. Our project manager was our architect first and he did the design. He designed the reno and recommended the builder. Our builder was not interested in managing all aspects of the renovation and the architect said he could take on the role of project manager - for a (somewhat hefty) fee of course. 

Grumpy_chap said:

VintageJedi said:

it’s unclear whether liability lies with the project manager, the builder, or the drainage company

The drainage company will have surveyed the drains they were asked to survey.  If they were asked to camera two drains and there were three, the drainage company would only have surveyed the two drains they were asked to have surveyed.  The report may have referenced the other drain as present and not surveyed.  
What did the scope of works given to the drainage company specify?
What did the report say?

Who did the design?
Was the project design and build by the builder?
If the builder was aware of the drain, their construction techniques should have allowed for build over without damaging the drain regardless of the age / condition of the drain.

Were the drains surveyed public drains?  If so, was there a formal build over agreement in place?
Was the drain that was not surveyed and subsequently collapsed a public drain?

The drainage company surveyed the public drains and there was a formal build over agreement in place. However, they only surveyed 2 out of the 3 private drains on our property. The third drain was somehow never surveyed, so we don't know what condition it was in before our downstairs bathroom and washing machine was connected to it. Best guess is that it was damaged during construction.

We have never lived in this house before so we don't know the original state of that soil pipe. We bought the house and then gutted it right back to the bricks. It was then repaired according to the PRC home repair scheme and we were issued a PRC certificate by an accredited structural engineer.

The drainage company was hired to do a site survey - this is what we have been told. Because we weren't the ones to hire them, the drainage company wouldn't even give us (the homeowners) a copy of the first report without our PM's permission - which he granted. The third waste pipe (serving downstairs bathrooms, washer, and utility) is not included in the first report.

We asked the drainage company for clarification on whether they were aware of the existence of a third soil pipe at the time of the March 2024 survey, and if so, why no attempt was made to survey it. Their reply was, "Any correspondence between us and PM is subject to GDPR & will not be given unless instructed by him in writing."

Bottom line: we don't know what they knew or what they were instructed to do.

Aretnap

VintageJedi said:

Why would Aviva deny our claim, yet potentially provide legal cover? 

Buildings/contents insurance and legal cover are completely different types of insurance, which just happen to be sold together.

Buildings insurance covers your home against some specific risks which might cause damage to it - fires, floods, storms, subsidence etc. The legal cover that is sold with it covers legal assistance for a wide range of disputes, including things like personal injury, medical negligence, employment tribunals, consumer law etc etc.

So it's not at all unusual for something not to be covered by home insurance but to be potentially something that you could use your legal cover to pursue. If you are unfairly dismissed from your job or if your surgeon botches your operation these aren't things that you can claim for on your home insurance, but the legal cover that comes with it might still cover the cost of suing your boss or your surgeon.

DullGreyGuy

VintageJedi said:
What do you know about Arc Legal? Why would Aviva deny our claim, yet potentially provide legal cover? I'm uninformed in the world of insurance, and I need to remedy that. 

Arc Legal is part of the AmTrust group of companies, they are an MGA, so not an insurer themselves but have delegated authority from others to sell their own insurance without reference back to the capacity provider. DAS/ARAG used to by far the biggest player in this space but Arc have made significant inroads for those not wanting to write their own LE cover. 

In this case though the policy is underwritten by Aviva and they are using Arc as a claims handling service (TPA). Different sections of your policy have different terms, they may have different insurers and/or claims handlers. Any claim should be properly assessed against the relevant sections by the relevant claims teams. 

LE can also be slightly different too because the economics of the insurance are different. With LE on Motor, at least before the whiplash reforms, you could give it away and still directly make a profit on it and not just through an uplift in your motor sales. Home LE is not as good unfortunately but you can still see claims that are revenue streams and so may decide to cover a claim that technically is out of the scope of the policy. 

ifonly2025

VintageJedi said:

This post is a bit long. There’s a short summary up front for the TL;DR crowd. The longer, detailed read is below, my questions at the end. Thanks.

Short Summary

We had an extension built. The project manager instructed a drainage survey before concrete was poured, but one of the main soil pipes—serving bathrooms and laundry—was never surveyed. That pipe is now likely collapsed beneath our new floor, causing flooding and rendering rooms unusable. The builder proceeded based on the incomplete survey, and the project manager either missed or ignored the omission.

The damage isn’t covered under the main policy with Aviva, but we do have legal expenses cover. Aviva referred us to Arc Legal, and I’m currently filing a claim. The case is complex, and it’s unclear whether liability lies with the project manager, the builder, or the drainage company.

Main Takeaways

1. The project manager advised us to hire a drainage company for a CCTV site survey. He chose the company; we paid.
2. The drainage company failed to survey one of the three soil pipes. No explanation provided.
3. The PM either didn’t read or didn’t notice the pipe was omitted from the report.
4. The builder poured concrete and built over the site without confirming full clearance. He now claims he trusted the PM’s word and never read the report.
5. Aviva says the damage isn’t covered under our home insurance policy—but legal expenses cover might apply.

---

Details

Background

In January 2024, we hired a building contractor and a project manager to oversee a whole house renovation and build an extension on our house. Our PM in April 2024 asked us to pay for a drainage company to do a CCTV site survey to make certain the drains were all clear before building over a public drain and pouring concrete. Our building contractor was onsite at the time at the time of the CCTV survey, our PM was not.

The Foul-up & Project Manager

Fast forward a year. We moved into the house at the end of April 2025. After about a week, water began coming up through the downstairs shower tray – and we had a minor flood. The water company did a CCTV survey – no problem on their end.   We asked the PM to see the original site survey report. He sent it and called us at the same time. Apparently, there are THREE waste pipes leading away from our house – and only TWO were surveyed.  He claims to not have known about it. Worth noting: the PM was generally incompetent, and my husband took over most of the project management. The PM effectively disappeared after we paid him in full. Lessons were learned.

The Drainage company

Mid-May 2025 - the original drainage company came to do another CCTV survey. We had to excavate our brand new flooring to access the third pipe. They couldn’t get the camera down the line—it appears completely blocked. They blasted gallons of water and blue-dyed water down the pipe, yet no trace of flow showed up in the manhole. No one knows where that water is going. This is unsettling news to me.

None of this appears in the report we received. When asked about it, they refused to discuss their correspondence with the project manager, citing GDPR rules. Then they sent us a bill for £754.

The Builder

That same evening, the building contractor came over and said he would fix it – great! He would need to dig up our floors down through to the concrete. He promised to get back to us in 2 weeks which was over 2 weeks ago.” He has a history of overpromising and running late (10 months over schedule, costing us over £10k in delays). We have little confidence he’ll return any time soon. I'm worried he could simply disappear on us.

Insurance and Legal cover

We didn’t have building insurance during the extension (don’t ask, I was unaware, it’s a touchy subject).  We bought an Aviva policy shortly before we moved back in. When the flooding occurred, they confirmed that underground pipes aren’t covered—but we do have legal expenses insurance.

Aviva Legal referred us to Arc Legal, who are now assessing whether our legal claim qualifies under the policy. However, because the original drainage survey occurred before the policy was active, they warned me it could be rejected. I’m still assembling documentation and submitting the claim.

Questions

• What are our next steps?

• Should we be looking for our own solicitor regardless of Arc Legal’s response?

• Are we now at risk for subsidence or structural damage from leaking or unconnected waste pipes? Or worse, our neighbours?

• Should we upgrade our insurance policy with better coverage for hidden damage, building work, or subsidence?

• What happens if additional issues (from the same build) are discovered in future -will we be covered under our current policy?

Hi everyone,

I'm new to this forum, but I've been following the discussions about the recent drainage issues with interest. It seems like the legal and insurance ramifications have been thoroughly covered, which is incredibly helpful.

I'm currently dealing with a similar, very frustrating blocked drain situation myself. While navigating the complexities of who's responsible and what's covered, my immediate concern has been finding a practical, step-by-step way to actually fix the blocked pipe and discover where the water is disappearing.

Based on my experience and some valuable advice I've received, I wanted to share a targeted approach to diagnosing and resolving the physical blockage. This focuses on the most efficient and cost-effective way to get answers from a drainage professional.

Here’s a possible solution for tackling the blocked drain itself, starting from the source

Step-by-Step Guide: Tracing & Diagnosing the Blocked

Phase 1: Immediate Actions & Preparation (You can do this yourself)

1.      Stop ALL Usage of the Affected Drainage: This is critical. Absolutely no more water down that shower, or any other fixture that you suspect might connect to the same blocked pipe. This prevents further flooding/discharge and allows the pipe to potentially dry out a little, which can aid certain diagnostic tools.

2.      Identify the Affected Appliance: Confirm it's primarily the downstairs shower tray.

3.      Isolate the Appliance (if applicable):

o   Shower: There won't be an isolation valve on the shower waste pipe itself. The isolation is usually for the water supply to the shower mixer. However, you can simply stop using the shower.

o   Toilet (if it were the affected appliance): As discussed, you would isolate the water supply to the cistern via the isolation valve.

o   Sink/Bath: Simply stop using the tap.

4.      Clear the Area for Access: Remove anything obstructing access to the shower tray (e.g., shower screen, boxing around the tray, flooring leading to it if you know the access point). If the tray needs to be removed for direct access to the pipe, be prepared for that.

Phase 2: Professional Diagnosis - Targeting the Source (Engage a Reputable Drainage Company)

1.      Engage a Reputable, Independent Drainage Company:

o   Crucial Qualities: Look for companies with good reviews, modern equipment (CCTV, pipe tracing, high-pressure jetting), and expertise in finding complex drainage issues, not just clearing simple blockages. Ask if they have radio-locating/sonar tracing equipment.

o   Explicit Instructions to Them (Crucial for Cost-Effectiveness):

§  "We suspect a third, untraced waste pipe is blocked. Water is backing up in our downstairs shower tray. We need you to identify the pipe and its ultimate discharge point, and then clear the blockage."

§  "Our primary access point for investigation is the waste outlet of the downstairs shower tray."

§  "We require a full CCTV survey starting from the shower waste, and simultaneous pipe tracing/locating of that specific pipe run."

1. On-Site Process with the Drainage Company:

• A. Accessing the Shower Waste: The drainage engineers will likely need to gain direct access to the shower trap and the waste pipe immediately beneath it. This may involve:
• Removing the shower waste grid/cover.
• Potentially removing the shower tray itself if direct access to the trap and pipe isn't possible from above or through an access panel. (This is less likely for a simple CCTV insertion, but may be needed for thorough access or if the blockage is right at the trap).
• Most commonly: They will feed the CCTV camera from this point, as it's the direct source of the problem.
• B. CCTV Survey & Blockage Identification:
• The camera will be inserted into the waste pipe from the shower.
• They will identify the nature and location of the blockage (e.g., debris, fat build-up, root ingress, collapsed pipe, dislodged joint).
• They will also look for any evidence of the pipe being disconnected or broken before the blockage.
• C. Pipe Tracing/Locating (Simultaneous or Immediately Following CCTV):
• This is the key to solving "where is the water going?". The CCTV camera they send down often has a small transmitter (sonde) built into its head.
• An engineer will use a handheld receiver/locator device above ground to pick up the signal from the camera/sonde as it travels down the pipe.
• This allows them to physically trace the exact path of the pipe underground, marking it on the surface.
• Critical Outcome: This tracing will tell you:
• The route of the pipe: Does it go under your extension? Towards the garden? Towards a neighbour's property?
• Its terminus: Does it lead to a known manhole that was previously missed? Does it simply terminate in the ground? Does it join another drainage system (e.g., a rainwater drain, or a neighbour's foul drain)?
• Disconnections/Breaks: If the camera or the tracing signal disappears, it indicates a significant break or complete disconnection.
• D. Report & Recommendations:
• Insist on a comprehensive written report, including a diagram of the traced pipe's route, footage/screenshots from the CCTV, and a clear explanation of what was found (type of blockage, location of problem, suspected discharge point).
• They should then recommend a solution (e.g., high-pressure jetting, excavation, pipe lining).

Phase 3: Repair & Reinstatement (Based on Diagnosis)

1.      Review the New Drainage Report: This report is your roadmap. It tells you exactly what needs to be done.

2.      Contact the Original Builder (Again): Armed with this definitive report, present it to the original builder. Reiterate his responsibility to fix this, as it stems from work under his oversight, and provide him with a firm, short deadline to agree to commence repairs.

3.      Obtain Quotes for Repair: If the original builder is unreliable, get quotes from other reputable drainage/groundworks companies for the specific repair identified by the new report. This might involve:

o   High-Pressure Water Jetting: If it's just a simple blockage.

o   Localized Repair/Lining: If it's a crack or break but the pipe is otherwise intact.

o   Excavation and Replacement: This is the most likely scenario if the pipe is collapsed, disconnected, or discharging into the ground. This will involve digging up your new floor again.

4.      Execute the Repair: If the original builder doesn't step up, proceed with the most suitable quote from another company.

o   Document Everything: Take photos/videos throughout the excavation and repair process. This is vital evidence.

o   Post-Repair Survey: Ensure a final CCTV survey confirms the repair is successful and the pipe is flowing correctly.

5.      Reinstatement: Once the pipework is fixed and passed, you'll face the task of reinstating the floor and any other disrupted finishes.

In my opinion this is the best and most cost-effective way

·        Targeted Approach: You're not randomly digging or surveying. You're starting at the known point of failure.

·        Reduced Scope: By starting from the appliance, you're directly investigating the problematic pipe, rather than trying to figure out which of multiple external manholes might be relevant.

·        Faster Diagnosis: Directly accessing the pipe where the problem manifests gets you answers quicker.

·        Clearer Evidence: The CCTV and tracing from this specific point will provide undeniable evidence of the pipe's condition, route, and any failures, which is crucial for your legal claim.

·        Minimised Unnecessary Work: This approach minimises the chance of a drainage company doing irrelevant work or surveys that don't directly address your specific blocked pipe.

Hope this helps, bear in mind this is one solution

Sincerely

Ifonly2025