Cesspit overflow: what to do right now

Why this is urgent

Untreated sewage on the ground or coming back into the house is a Category 3 public-health hazard. The bacteria, parasites, and viruses present in the waste cause serious illness through skin contact, ingestion, or inhalation — particularly for the elderly, young children, and immunocompromised people.

It’s also potentially illegal to leave it. Allowing sewage to enter a watercourse is an offence under the Environmental Protection Act and can be reported to the Environment Agency. Acting quickly to contain and remove it is the right thing legally as well as practically.

Step 1: Stop the input

The tank can’t take any more. Adding more wastewater makes the overflow worse. So:

• Don’t flush toilets. If you must use one, leave the flush — we’ll deal with it.
• Don’t run washing machines, dishwashers, or showers.
• Avoid using sinks for anything beyond filling a kettle.
• If you have animals using the same water — horses, livestock — keep their water from going down internal drains.

For a household of four, fully stopping water use buys roughly 4–6 hours of breathing room. That’s usually enough.

Step 2: Contain the overflow

If sewage is on the ground outside, try to keep it from spreading further:

• Block the path it’s taking with sandbags, planks, or even a row of bricks. Even a small barrier slows the flow significantly.
• Cover affected ground with sand or sawdust if you have it — it absorbs the worst of it and makes cleanup easier.
• Don’t hose it away into a stream, ditch, or drain. That makes it the watercourse’s problem and is the move that gets you reported to the EA.

If sewage is inside the house, lay old towels along the affected drain to limit the spread, open windows to ventilate, and keep the area off-limits.

Step 3: Document for insurance

Take photos before, during, and after. Note the time. Keep any text messages from us with the slot and price. Most household insurance policies include some cover for sewage backup but require evidence — get it now while it’s easy.

Step 4: Wait for the tanker

We’ll usually be with you within a few hours of the WhatsApp. We carry the equipment to handle overflow situations — long hose runs, additional tanker capacity if the spill is significant, and a clean-water rinse to settle the immediate area before we leave.

The cost is normally the standard same-day callout (from £220) plus a per-litre rate if the spill is large. We confirm the firm number on the phone before we set off.

After the emergency: stopping it happening again

An overflow nearly always means one of three things:

1. Schedule too long. The tank reached capacity faster than expected, often because of a change in household use (extra people staying, big laundry day) or because the tank is undersized for current use. We’ll recommend a tighter interval.
2. Soakaway failure (septic tanks). The tank itself isn’t at fault; the soakaway field has stopped accepting effluent, often because of saturated ground in winter or accumulated bio-mat. Worth a soakaway investigation.
3. Tank failure. Less common but does happen — cracked walls, collapsed seams, lid failure. We’ll spot signs of this when we empty and tell you what we see.

Whichever it is, the next step is a routine that prevents a repeat. Set up a regular schedule with us.

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Last updated 2026-05-07. Written by the TankAway operator. We empty tanks for a living — this is the advice we’d give a friend.