What is a sewage pumping station?

A sewage pumping station is a sealed underground chamber that collects wastewater from a property and pumps it uphill to wherever it needs to go — usually a public sewer in the road, but sometimes a septic tank or treatment plant on higher ground. It exists because gravity drainage only works downhill, so any property sitting below the level of the sewer needs its sewage lifted. A domestic one is typically a chamber of around one to two cubic metres containing one or two submersible pumps, float switches that turn them on and off, and a control panel with an alarm.

Why does my pumping station alarm keep going off?

The alarm means the level in the chamber has risen above where it should be, so something is stopping the pump clearing it. The most common causes are a float switch fouled by a crust of fats and solids on the surface, a pump blocked by wipes or rags, a tripped electrical supply, or a pump that has simply worn out. A crust on the surface is very common and interferes with the float directly — the pump never gets the signal to run, or runs at the wrong time. Do not ignore an alarm: the chamber has limited spare capacity and once it is full, sewage backs up into the property.

How often should a sewage pumping station be emptied or serviced?

A domestic pumping station generally wants servicing every 12 months, and many manufacturers recommend two visits a year. A service should include cleaning the chamber and float switches, checking and testing the pumps, and confirming the alarm works. A station is not like a septic tank — it is not storing sewage to be emptied on a schedule, it is moving it. If yours genuinely needs emptying often, that is a symptom of something else, usually a failing pump or a build-up that should have been cleaned off at a service.

What does it cost to empty or service a private pumping station?

Emptying a chamber by tanker in Cornwall is priced as a callout rather than by volume, so a small chamber costs close to what a full septic tank does — quotes in August 2026 were running £300–£350. That is because you are paying for the tanker's time and the disposal run, not the litres removed. A pump station service, which cleans the chamber and checks the pumps and floats, is a different job and treats the cause rather than the symptom. If a crust keeps re-forming, repeated emptying is the expensive way to solve it.

Can I put anything down the drain if I have a pumping station?

No — pumping stations are less tolerant than mains gravity drainage, not more. Wet wipes, sanitary products, cooking fat and oil are the main killers. Wipes wrap around the impeller and jam the pump; fats and oils cool, solidify and form the surface crust that fouls float switches. Anything that would be a nuisance in a sewer becomes an expensive mechanical failure in a pumping station, because there is a moving part in the way.

Private sewage pumping stations explained

Plenty of Cornish properties sit below the lane that serves them. When that happens, wastewater cannot run to the sewer under gravity, so it collects in a chamber and gets pumped up. That chamber is a sewage pumping station, and if it is yours, it is the piece of drainage most likely to cost you money unexpectedly.

Before reading further, it is worth checking whether it is even yours. A lot of private pumping stations transferred to the water company in 2016 — see is my pumping station mine or the water company’s?.

What’s actually in the chamber

A domestic pumping station is usually a sealed chamber of roughly one to two cubic metres, containing:

One or two submersible pumps. Two is better: they alternate, and if one fails the other carries on while you get it fixed.
Float switches. Simple tethered floats that rise with the liquid level and tell the pump to start and stop. There is normally a separate high-level float wired to the alarm.
A rising main — the pipe carrying pumped sewage up to wherever it discharges.
A control panel, usually on a wall or post nearby, with an alarm light and buzzer.

The chamber holds a working volume plus some spare capacity, which is what buys you time when something goes wrong. It is not a storage tank and it is not treating anything.

What goes wrong, in order of likelihood

A crust on the surface. Fats, oils and solids float, cool and form a mat across the top of the chamber. That mat fouls the float switches, so the pump doesn’t start when it should — or starts and stops erratically. This is the single most common fault and it is entirely caused by what goes down the drain.

A blocked pump. Wet wipes are the main offender. They don’t break down, they wrap around the impeller, and the pump either jams or runs without shifting anything.

Electrical faults. A tripped breaker, a failed float, a burnt-out pump. Anything with a motor immersed in sewage eventually dies.

Ignored alarms. The alarm is the last line of defence. Once the spare capacity is used, sewage backs up to the lowest point in the property — which is usually a downstairs shower or toilet, and is a far worse day than the one where you called someone about the alarm.

What to do when the alarm goes off

Stop using water in the property — no washing machine, no baths, minimal flushing. Every litre you send down makes it worse.
Check the control panel for a tripped breaker or an obvious fault light. If a breaker has tripped, reset it once. If it trips again, stop and call someone.
Don’t open the chamber unless you know what you are doing. These are confined spaces containing sewage gases. Lifting the lid to look is one thing; leaning in is genuinely dangerous.
Call a drainage engineer, not just a tanker. Emptying the chamber will clear a surface crust and buy you time, but if the pump has failed or wipes have jammed the impeller, an empty chamber refills and you are back where you started at the next tanker price.

Emptying versus servicing — pick the right one

This distinction is where most money gets wasted.

Emptying is a tanker sucking the chamber out. It removes the crust along with everything else, so it often does fix a float-switch problem — but it treats the symptom. In Cornwall a tanker visit is currently £300–£350, and because you are paying for the visit and the disposal run rather than the volume, a part-full chamber costs almost the same as a full septic tank. See our emptying cost guide for why prices are where they are.

Servicing cleans the chamber and the floats, tests the pumps and checks the alarm. It costs money too, but it addresses why the crust formed and catches a tiring pump before it strands you.

If you find yourself booking a tanker more than about once a year, you are buying the wrong service.

Keeping it out of trouble

The rules are short and they are mostly about the kitchen and bathroom:

No wipes. Not “flushable” ones either — the word is marketing, not engineering.
No fat or cooking oil down the sink. This is what becomes the crust.
No sanitary products, nappies or cat litter.
Get it serviced annually, and make sure whoever does it actually tests the alarm rather than just glancing at it.

Do those four and a pumping station is genuinely low-drama. Ignore them and it becomes the most expensive part of your drainage.

Sources: Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011