house with septic tank

[carmanmemoranda]

I'm going to look at a house for sale, and it has a septic tank.

I know next to nothing about these. What should I be looking for, to find out?

What do I need to know overall?

 

[Pinoy]

Hello...we have lived in three houses with a septic tanks and treatment system.
Get a septic tank survey ! They are not expensive, I recall a few hundred quid.
As a rule, if it stinks, there is something very wrong, even in summer.

 

[Hugh Jaleak]

I would get someone who knows about Septic Tanks to have a look and advise on what is there, and what might/will be needed to bring it up to standard. The Environment Agency has clamped right down of discharges from septic tanks in recent years, if they find it and it's not up to their standards, remedial works can be very expensive.

A little light reading, https://www.gov.uk/permits-you-need-for-septic-tanks

If you're not sure of anything, come back and ask, I will do my best to help.

 

[carmanmemoranda]

Appreciate that and thanks.

At this stage I'm just looking at the house and deciding if I want to go further.

Anything obvious I should be looking for? Initial look at the house and no smells, and assured that the tank is "serviced and emptied" once a year.

Will pay for survey if I go for the house, but trying to decide if I want to get to that stage, and so far, it looks possible

 

[charliegolf]

Anything obvious I should be looking for?

Toilets flush without hesitation; basins drain same. Should the soakaways be fouled up, the 'onion' bit will be holding more water than it should and the drainage will be slow. Ask to look in the hatch.

 

[Hugh Jaleak]

Anything obvious I should be looking for? Initial look at the house and no smells, and assured that the tank is "serviced and emptied" once a year.

Type and Construction of Tank would be my first question. Old brick built or the fibreglass 'Onion' shaped type are more likely to be unfit for purpose going forward. These offer very basic treatment of the effluent, relying on the solids to settle out, and regular emptying is vital to prevent high concentrations of suspended solids leaving the tank in the clarified effluent, and blocking the Leachfield/soakaway.

Remember, nigh on every drop of liquid going into the tank, needs to go back out of the tank, it's the solids that need to remain. Blocked soakaway/leachfield will be expensive to repair/replace and tank will need constant emptying by a Licenced Contractor to prevent overflowing until fixed.

Safety is another concern, Children/Animals, will they be safe? Anyone/anything falling into a septic tank stands a very real chance of not coming back out alive. Not only the risk of drowning, but poisonous gases can be present, which will kill in seconds if inhaled in too high a concentration.

Anything with a power supply, e.g. the Klargester Biodisc, or something with a small compressor, pumping air into the tank is much more modern and may need very little in terms of an upgrade. If one of these modern versions needs to be installed to replace an existing tank no longer fit for purpose, be mindful, suck work is not going to come cheaply.

The modern systems though will not stand as much abuse, they do need regular servicing and emptying to ensure continued service and adequate treatment of the effluent. Factor cost of this into the annual budget.

 

[George_engineer]

Make sure you're ok with the terminology.

A cess pit is a pipe to a sealed tank which is regularly emptied. These are acceptable if in good condition.

A septic tank which directly discharges to a watercourse is no longer acceptable.

A septic tank which discharges to a drainage field (not a soakaway) is acceptable.

In recent years, it more usual to get a sewage treatment plant. STPs can discharge to a watercourse. These generally require a power supply.

All of them need annual maintenance.

General binding rules: small sewage discharge to a surface water

How to meet the general binding rules if your septic tank or small sewage discharge treatment plant releases (discharges) waste water to a surface water.

www.gov.uk

The current owner needs to make sure the system complies, or sometimes the cost to do the upgrade is knocked off the sale price as all buyers need to get this checked.

 

[Ivor Windybottom]

If it needs replacing, if you want to sit in a chair while someone else does everything then £20k is probably realistic.

If it discharges to surface water then it probably needs replacing, see all the very useful info in the post above.

If it discharges to percolation pipes then they probably need replacing.

If it's all old then you're probably opening a can of worms and could well end up replacing all the underground pipes.

I took a hybrid-DIY approach with ours - I bought one, paid a groundworks company to install it according to the manufacturer's specs. Then I did all the pipework. This probably saved around £10k.

I found that the 3 drainage companies I got quotes for seemed like cowboys. Don't take their word for it being done properly, get the specs and ask them if they'll do it like that. One of them said he didn't bother encasing it in concrete but uses gravel, another stormed off in a huff that I was daring to ask.

 

[carmanmemoranda]

Apparently it's a biodigester.

Now what do I ask or need to know ?

 

[George_engineer]

Install date and sign off from Building Control and service record. If not available you may want an independent inspection.

 

[Ivor Windybottom]

It sounds like it's reasonably modern. The downside of biodigesters is that they usually have moving parts so can fail. There's a drum that rotates, exposing the contents to the air. More modern ones achieve the aeration by blowing bubbles through it, using an air pump that can be located completely outside of the thing - mine sits in a plastic box above ground level. Much less to go wrong, no mixing of electrics and water, the pump is easy to access if it needs repair or replacement. Mine supposedly needs new pump diaphragms every couple of years, but still works fine after 3. Mine has a pressure switch that lights a red neon in the house if the air isn't pressurised, so far all is well.

It may be worth getting it checked. Or just lift the lid and look for yourself. If it's not turning then it needs fixing - probably just repairing rather than replacing the whole thing. If it is turning then it will need fixing the next time it stops. They all have ongoing needs, this is just reality. The upside is that you don't have to pay the £100s per year of sewerage charges on your water bill so consider this saving to be your budget for emptying and maintenance. Also it will cost you around £100 per year in electricity. Overall, ignoring the installation cost, you'll probably pay similar or slightly less than the townies do.

If you like the house, make an offer and get on with it before someone else does. The absolute worst case is probably a small percentage of the sort of money you're talking about anyway.

 

[carmanmemoranda]

Thanks all.