Septic tank question

linc1464

Dear all,

The house that my wife and I are looking to buy has a septic tank drainage system, which was inspected today. Apparently it is filling up faster than expected. The inspector noticed that downpipes from the roof were carrying water into it and that they don't recommend this.

Please excuse me as I have no idea about how any of these systems work. But, what does one do to fix this situation and where instead should the downpipes drain to? Is this a cheap fix potentially?

Many thanks
Steve

Guest101

How strange, surely that cost a fortune to empty so often.


Without seeing a layout I don't know where else you would direct them. Perhaps a water tank, or simply to drain away elsewhere.

AdrianC

If it's a septic tank, then the extra water shouldn't be an issue - because it should always be full. If it's overflowing, then the soakaway fields may be blocked.

If it's "filling", then it's a cesspit, not a septic tank, and ALL liquid that goes in needs to be emptied out - regularly, and expensively.

If you really want to redirect the downpipes, then you'll need to dig a soakaway somewhere, and route the water to it - a french drain (a trench of gravel) is the cheapest and simplest way.

Hoploz

There is some confusion here ... A septic tank doesn't really 'fill up.' it has a drainage field where the liquids drain off. It's normally just waste water but if it is taking the rainwater too it shouldn't make too much difference to the way it works.

I think the inspector might just be making an observation about the surface water, or there's is some sort of blockage at the out end. There are different types of system but usually there is a drainage field of pipe work under the surface of the ground which absorbs the liquid once filtered. Drainage fields can fail but I wouldn't think taking excess rainwater would be the cause.

G_M

Who as the 'inspector'? A surveyor (who will not know much about septic tanks - eg that they are permenantly full).

Or a drainage/ septic tank specialist, who would know the difference between a cess pit and a septic tank?

Davesnave

I beg to disagree. While septic tanks may be able to cope with run off from the roof, it's not good practice to make them do so. Over time, the leach field becomes less efficient, so burdening it with thousands of extra litres isn't a great idea.

This is especially true in winter, when the water table rises and the leach field itself can become waterlogged, leading to boggy ground and water at the surface. We all know this isn't supposed to happen, ever, but it does.

The correct place for water from the roof is probably a water butt or IBC container with the surplus directed into a soakaway. Modern soakaways are based on plastic crates isolated from the surrounding soil by a membrane and surrounded by gravel. They're easy to install once the hole has been dug somewhere appropriate, such as where there's a bit of fall in the land and at least 5m from the house.

Edited to add: My soakaways were constructed over 40 years ago and seem to be nothing more than perforated pipes directed into about a half tonne of beach gravel. Nevertheless, they work and we had no idea exactly where they were until a couple were unearthed by recent building.

nickcc

We had an extension built to a cottage back in 1998, the builder plumbed all the drainage, both foul and surface, into our new block built septic tank. When the building inspector came to inspect the final works he refused to issue a completion certificate until we had built seperate soakaways

We have had both septic tanks and cesspits, all have had the liquid drain off into a seperate soakaway but both types eventually needed the solids removing.

G_M

nickcc wrote: »

We have had both septic tanks and cesspits, all have had the liquid drain off into a seperate soakaway but both types eventually needed the solids removing.

Surely by definition a cesspit cannot drain off into a seperate soakaway?

nickcc

G_M wrote: »

Surely by definition a cesspit cannot drain off into a seperate soakaway?

Why not the liquid has to go somewhere so when the solids build up and block the missing brick work the liquid can still run off from the top of the cesspit and not flood the surrounding ground.

AdrianC

nickcc wrote: »

Why not the liquid has to go somewhere...

The basic definition of a cesspit is that the liquids only leave in a tanker. Regularly. Expensively.

If there's a soakaway, then you need the liquid to be clean. So you need the munchybeasties, so it's a septic tank by definition...

G_M

nickcc wrote: »

Why not the liquid has to go somewhere so when the solids build up and block the missing brick work the liquid can still run off from the top of the cesspit and not flood the surrounding ground.

As per my link in post 5 above:

the difference between a cess pit and a septic tank?