Drainage and septic tanks

The kitchen waste drops into the hopper of a rainwater pipe. Has a misconnection been proved?

Not underground. The survey can see a waste pipe entering a rainwater hopper, which is the wrong place for foul water to start, but it has not traced the buried pipe, dyed the system or camera-surveyed it. The visible entry is the finding, and the rest is unproved.

Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.

What is the fuller explanation?

A hopper on a downpipe is for rain. A sink, washing machine or dishwasher waste in that hopper sends foul water into whatever the rainwater pipe joins. That may be a surface-water sewer, a soakaway, or a combined drain. The survey sees the hopper. It does not see the outfall. Call it a visible discharge into a rainwater fitting, not a completed trace. Approved Document H describes proper drainage for controlled building work. It does not certify this kitchen, and it is not a grade on a camera report. No grade should be invented.

The opposite mistake, rain into a foul gulley, is a different pipe. Do not paste one description onto the other. A drainage firm can confirm the destination if you need that before exchange. Lifting a chamber, if one was lifted, may show flow when the sink runs, which is useful and still not a map. RICS surveys are visual unless an extra was agreed. Ask the firm to start at this hopper. Do not tell them every waste in the house is wrong. There is no price in the building-regulations document for “sorting the hopper”.

What should you ask your surveyor?

Which waste enters which hopper?
Did you trace it beyond the hopper?
Are you describing a visible pipe, not a proved underground route?

What are the typical next steps?

Photograph the hopper if you can do it safely. Do not disconnect the waste.
If you instruct a drainage firm, start them on this pipe.
Keep rain-into-foul as a separate note if that also exists. Do not blend the two.

Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.

Also asked about this

Does a smelly hopper prove the whole street is misconnected?

No. It proves this hopper is worth tracing. The survey has not mapped the street.

Is a hopper the same thing as a foul gulley at ground level?

No. A hopper is up the pipe. A gulley is at the ground. Name the one the survey saw.