Outside Drain Overflowing? What to Do First
In short
An overflowing outside drain means the underground pipe is blocked. Stop everyone in the property using water, keep people and pets away from the standing water, then lift the inspection chamber covers in turn from the house towards the boundary. The blockage is between the last full chamber and the first empty one. If the chamber nearest the boundary is full, call your water company first — a shared or public sewer is their responsibility.
An overflowing outside drain means the underground pipe is blocked and waste water has nowhere to go. Unlike a slow sink, this one gets worse every time anyone in the house uses water, so the first job is to stop adding to it.
It is also the point at which the question of who pays becomes worth asking, because a large proportion of these blockages sit in shared or public sewers that your water company maintains free of charge.
Stop using water in the property
Tell everyone in the house not to flush toilets, run taps, or start the washing machine or dishwasher. Every litre used goes straight to the overflow point. This alone often stops the level rising while you work out the next step.
Keep children and pets away from the standing water, and wear gloves. Do not attempt to clear a chamber that has overflowed into a confined space.
Find out where the blockage is
Lift the inspection chamber covers on your property in turn, starting with the one nearest the house and working towards the boundary. Use a screwdriver in the lifting keyholes, and lift with your legs — cast iron covers are heavy.
- Chamber near the house full, chamber near the boundary empty — blockage is between the two, on your land.
- All chambers full including the last one before the boundary — blockage is downstream, often in a shared lateral drain or the public sewer.
- Only one appliance affected and all chambers clear — the problem is in the waste pipe inside the property, not the drain.
Who is responsible
Drains inside your boundary serving only your property are yours. Lateral drains beyond your boundary, and shared drains serving more than one property, have been the water and sewerage company's responsibility since 2011 — and they will attend and clear them at no charge.
If your checks show the last chamber before the boundary is full, call your water company first. It costs nothing and it may be their job. If they attend and confirm the fault is on your side, that is when to call a drainage engineer.
What clearing it involves
Most blocked underground drains are cleared the same day with rods or high-pressure jetting, usually inside an hour. Jetting also scours the pipe wall, which matters when the cause was fat or scale rather than a single object.
If the same drain floods repeatedly, or the jetting head keeps stopping at the same point, ask for a camera survey afterwards. Recurring flooding almost always means root ingress, a displaced joint or a partial collapse holding material back.
Still not resolved? 24/7 Emergency Drain Callouts can help
Drain blocked, sewage backing up, or water where it shouldn't be right now. Our engineers are available 24 hours a day with no call-out charge, and you get a fixed price before any work starts.