What septic tank cleaning actually means
Septic tank cleaning usually means one of two jobs. A routine empty, often called desludging, removes the liquid and settled sludge from the tank by vacuum tanker. A full clean goes further: once the tank is empty, the firm jets or rinses the chamber so the inside is washed, not just pumped out. Mantank describes high-pressure jetting as the way to “properly clean the tanks surface area”, and MyJobQuote lists backwashing or rinsing the chamber after emptying as part of a clean.
The trouble is that most firms use “cleaning”, “emptying” and “pumping” as if they mean the same thing. One firm’s “clean” is a straight pump-out; another’s includes jetting. A firm may also check the inlet, outlet and baffles while the tank is open, so ask what is included before you agree a price.
Routine empty
- Liquid and sludge removed by tanker
- Tank walls are not washed
- Priced by tank size and access
Full clean
- Liquid and sludge removed by tanker
- Chamber jetted or rinsed after emptying
- Usually charged as an extra on top of the empty
Clean or empty: which do you need?
Most tanks only need a regular empty. A full clean is an occasional job, booked when something has gone wrong or when you do not know what state the tank is in. The four situations below are our own advice, not a legal rule.
1. Routine empty is enough
Nothing is wrong, the drains run freely and the tank is on a regular schedule. Book an empty and keep the paperwork.
2. Slow drains, smells or a blockage
Ask for a clean and a check while the tank is open. The GOV.UK general binding rules say a system with leaks, blockages or smells must be repaired, and maintained by a competent person.
3. Buying or selling a house
GOV.UK says maintenance records pass to the new owner “if you have them”. If there are none, ask for a clean and think about a septic tank survey as well.
4. Unknown history
New to the property and no records? Ask the firm exactly what the job includes, and get it in writing before the tanker arrives.
How often? For a septic tank discharging to the ground in England, GOV.UK guidance says to have the sludge removed “at least once a year or in line with the manufacturer’s instructions”. That covers the empty. Book a routine septic tank pump-out on that cycle, and add a full clean only when one of the situations above applies.
What septic tank cleaning costs
A clean is priced like an empty, plus extra for the jetting and the time on site. These figures come from the MyJobQuote cost guide (last updated 28/09/26).
The base price depends mostly on tank size. MyJobQuote’s figures for basic sludge removal:
| Tank size | Basic sludge removal | Source and date |
|---|---|---|
| 4,500 litres | £90 to £130 | MyJobQuote, last updated 28/09/26 |
| 8,500 litres | £150 to £200 | MyJobQuote, last updated 28/09/26 |
| 12,500 litres | £220 to £250 | MyJobQuote, last updated 28/09/26 |
| 17,500 litres | £260 to £300 | MyJobQuote, last updated 28/09/26 |
Add the clean on top of the row that matches your tank. Prices vary by region, access and tank size, so get two or three quotes and ask each firm whether jetting is included. Our guide to septic tank emptying costs breaks the numbers down further.
Cleaning products and your tank
A septic tank works because bacteria break the waste down. Household cleaners are fine in moderation; strong ones used heavily work against the tank. Scottish Water’s guidance (written for Scotland, but the chemistry is the same everywhere) puts it simply:
Fine in moderation
- Detergents and washing liquids
- Fabric conditioners
- Toilet fresheners
Use them “in moderation”, because they can upset the tank’s natural balance.
Use sparingly or bin it
- Bleach and disinfectants: sparingly, as they can kill the friendly bacteria
- Wet wipes, sanitary items and cotton buds: “bag it and bin it”
No product takes sludge out of the tank, so cleaners and additives never replace an empty. For the full list, read what not to put in a septic tank.
Check the firm is a registered waste carrier
Whoever cleans your tank also takes the waste away, and that matters to you. Under section 34 of the Environmental Protection Act 1990, householders must take the measures that are reasonable in the circumstances to make sure their waste goes only to an authorised person, and a registered waste carrier is one. GOV.UK says the company that removes your sludge “must be a registered waste carrier”. Checking takes a couple of minutes:
- Ask for the number. When you book, ask the firm for its waste carrier registration number.
- Ask for the certificate. GOV.UK suggests asking for a copy of the waste carrier certificate, at booking or from the driver on the day.
- Look it up. Search the Environment Agency register of waste carriers, brokers and dealers. Check the name matches the quote and the registration has not expired.
What we check, and what we do not
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We check registration only. We do not check workmanship, and we do not say which firms offer jetting, so ask each one what its clean includes.
Find a septic tank cleaning firm near you
We see the most cleaning requests from Devon, Cornwall, Cambridgeshire and Essex, but registered carriers cover the whole of England. Pick your county or region to see the firms that serve it. When you contact one, say you want a clean, not just an empty, so the quote covers the right job.
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Got a sealed tank with no outlet? See cesspit emptying instead.
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