The short answer
Good septic tank maintenance comes down to a short routine. Have the tank emptied at least once a year, keep rainwater and anything that won't break down out of the drains, look after the drainage field, and get problems checked early. Most septic tanks that fail do so because one of these slipped, usually the emptying.
None of it is complicated. The lists below cover the habits that make the biggest difference.
The dos
- Emptying at least once a year, or as the manufacturer says, is a legal requirement in England. Use a registered waste carrier and keep the receipt.
- Water-saving habits help. Spreading washing loads across the week, fixing dripping taps and sorting a running toilet all reduce the load on the tank.
- Keep records of emptying, inspections and repairs, plus a plan of where the tank and drainage field are. You must give this information to a buyer in writing when you sell.
- A look at the inspection chamber after the tank every so often shows whether the effluent is running clear. Building regulations suggest checking monthly.
- Grass is the best cover for a drainage field. It takes up water and keeps the soil open.
- Treatment plants need servicing in line with the manufacturer's instructions, normally at least once a year, as well as desludging.
- Act on warning signs. Slow drains, smells and wet patches are cheaper to deal with early.
The don'ts
- No wet wipes, nappies, sanitary products or cotton buds. They do not break down and they block pipes and pumps. Only toilet paper and human waste should go down the toilet.
- Keep cooking fat and oil out of the sink. Wipe pans with kitchen roll and bin it. Fat hardens into a thick scum layer and can block the outlet.
- Rainwater doesn't belong in the tank. Gutters, drive and patio drains should go to a separate soakaway or drain.
- Vehicles, sheds, patios and new trees should stay off the drainage field. Building regulations keep roads and paving off it, and roots invade the pipes.
- Heavy doses of strong chemicals can upset the bacteria. Normal cleaning is fine, but avoid pouring away large amounts of bleach, drain cleaner, paint, solvents or medicines.
- Additives are not needed. A working tank gets all the bacteria it needs from what goes into it, and no product replaces emptying.
- Never climb into the tank or lean in with the lid open. The gases can kill.
A simple yearly routine
| When | What |
|---|---|
| Monthly | Glance at the inspection chamber after the tank, and walk over the drainage field for wet patches or smells |
| Every year | Emptying by a registered waste carrier. Service and desludge a treatment plant |
| After heavy rain | Check for wet ground over the field and slow drains in the house |
| Before selling | Gather your records and consider a seller's drainage survey |
| Whenever something changes | An extension, more people living there or new symptoms are all reasons for an inspection |
What goes down the sink and toilet
Toilet paper is fine, though thick quilted paper breaks down more slowly. Our guide to toilet paper and septic tanks explains how to test yours. For cleaning products, see is bleach bad for septic tanks. Food scraps belong in the food bin or compost rather than the sink.
Looking after the drainage field
The drainage field is the part that costs most to replace, and it fails when solids reach it or the soil gets compacted or waterlogged. Regular emptying protects it from solids. Keeping vehicles off protects the soil. If you need to dig nearby for an extension or a new service, find out exactly where the trenches run first. Our guide to signs a drainage field is failing lists what to watch for.
An inspection every few years, or whenever something changes, catches problems while they are still small. Our septic tank inspections cover the tank, the pipework and the drainage field, and our treatment plant servicing keeps powered systems running. We don't provide emptying, so book that with a registered waste carrier.
