grey water tap?

November2

Hi, just moved into a property that has a septic tank, also in the garden there is a do not drink grey water tap.  Tap hasn't been turned on for months so wondering where the water is stored or does it come directly from the septic tank?  Unfortunately previous owner has left us no details of system or layout, would there be some type of filtration system buried somewhere for the grey water to pass through?  The run off for the septic is shown on the plans as outside the garden area yet part of the garden is sodden!  Any expert advice appreciated as its all new to me!

EricMears

FWIW,  I use (untreated) rainwater for WC flushing and my system involves pumping rainwater to a tank in loft from which WCs are supplied.  The system includes an outside tap that could in theory be used for watering but I mainly use it for clearing airlocks if the header tank ever runs out.

I'd think it more than possible that previous owner  has set up something similar for their 'grey water'.

Highly unlikely that grey water is coming from septic tank !  Grey water is usually the product of some fairly clean wastes - e.g. bath or shower water.  The stuff that goes to a septic tank ('black water') should be WC flushings and probably waste from dishwasher or washing machines which you wouldn't want anywhere near a grey water supply.

A conventional septic tank would never have effluent clean enough for reuse;  a 'treatment plant' might have (theoretically !) but it would be very bad practice to try and use it thus and in any case you'd need some sort of pump to recover that effluent and pump to storage.

HTH

Reed_Richards

On a warmer day, turn on the grey water tap and listen for the sound of a pump running.  The most obvious way of collecting grey water is to direct the run-off from your gutters to a tank, which is often buried.  This tank will need an inspection chamber so you can remove and service the pump as necessary, so look for a manhole cover or similar that is not associated with your septic system.

At this time of year a sodden area of the garden does not necessarily mean you have a leak or a discharge, it could just be a low-lying area.    

November2

Thank you for replies. The garden is all lawn and part of it is very wet, I used a step ladder this week to cut a tree and sank! That's why I wondered if the grey water if not being used out of the tap was being dispersed as an overflow into the lawn.  We do have clay soil though so possibly the cause. Will search for man hole covers, have no idea if the water is flushing toilet or not will have to check the loft and see what's up there.I  have found a large sunken hole with a hard plastic liner but it appears empty with leaves in the bottom, must be at least 6' deep and around 1.5' wide, no idea what it is, situated about 10' away from the septic tank.  

Reed_Richards

Okay, I have been thinking about one day getting a grey water system but all I have done so far is to make sure that all my toilets have their own water pipes into the loft so they could be switched over in future.  Some systems use a header tank in the loft for the grey water that flushes the toilets.  Other systems pump it directly from the (buried) tank.  You would channel the water from your roof downpipes to the grey water tank and provide the tank with an overflow to a soakaway, or a nearby stream could be an alternative.

If there is nothing at the bottom of your large sunken hole maybe the pump went wrong and was not replaced?  

November2

Had a look through the solicitor paperwork and found a not to scale map showing position of the drainage field for the septic tank, it appears on first glance to be quite far from the house but in fact is the lawned garden. I had planned to plant bushes and flowers but will now have to be careful on what I plant.  No mention anywhere about grey water system.  Will have to do more investigating, going to remove the leaves tomorrow from the sunken hole to see if anything at the bottom.

Reed_Richards

If your septic tank is overflowing then it needs pumping out.

EricMears

Reed_Richards said:

If your septic tank is overflowing then it needs pumping out.

That's a bit simplistic !

A septic tank is designed to overflow with the effluent going to some sort of land drain system where it can be absorbed by plant matter.

A treatment plant is a special case where the effluent has been cleaned up enough to be discharged into a water course.

Another system that gets confused would be a cess pit which should never be overflowing - it's just a holding tank until effluent can be pumped away (probably to a tanker).

There also seems a lot of confusion about different grades of water in this thread !

Grey water is cleanish stuff drained from inside the house that can be re-used in several ways (possibly after some sort of treatment)
Black water is foul drainage that needs to go to cess pit, septic tank or treatment plant.
The liquid that falls on roof and can be collected from gutters is simply rainwater and can be used for almost anything except drinking - though filtration is recommended for some uses (e.g. in washing machines).

theoretica

Are you confident it is grey water?  Some buildings have 'do not drink' taps and it is just to do with the plumbing and water coming from open or lead tanks - not grey water.  Any chance of tracing the pipes?

Reed_Richards

EricMears said:

A septic tank is designed to overflow with the effluent going to some sort of land drain system where it can be absorbed by plant matter.

A treatment plant is a special case where the effluent has been cleaned up enough to be discharged into a water course.

Another system that gets confused would be a cess pit which should never be overflowing - it's just a holding tank until effluent can be pumped away (probably to a tanker).

My only experience of a house with a "septic tank" was in North America.  Perhaps the design or the terminology is different there but "my" tank did need pumping out every so often. 

EricMears

My septic tank (actually a mini treatment works because it is continuously aerated) was installed with advice from my neighbour who had a conventional septic tank.   His system was installed in the 1960s and he claimed (he died a couple of years ago)  that it had never been pumped out.  Mine has now been in use for 22 years and the only occasion when anything has ever been pumped out was when the outlet was blocked with a 'fat ball'.

OTOH,  a 'cess pit' needs to be almost completely emptied regularly (usually every couple of months but it depends on capacity and input rate) and any sort of overflow would be a disaster..