Drainage and septic tanks
What did the visit record about a crust on a septic tank, about no emptying ticket, and about a volume the cover glance does not measure?
It recorded a crust seen on a septic tank, the absence of an emptying ticket, and the fact that a glance at the cover does not measure volume. A septic tank is not a cesspool. A cesspool only holds sewage until it is emptied, while a septic tank is meant to settle solids and let liquid flow on. The survey did not measure sludge depth and did not test the outlet. Crust, missing ticket and unknown volume stay three limits, not a capacity result.
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 crust is the scum layer that forms on a septic tank. Seeing it through a cover, or seeing only the cover, does not say how deep the sludge is or how much working volume is left. An emptying ticket is the usual paper for when a tanker last came. No ticket in the pack means that date is unknown, not that the tank is full and not that it was emptied recently. The glance did not dip the tank. Volume was not measured.
Ask the solicitor for invoices or tickets from the emptying contractor and for any permit or exemption that applies to the discharge. A drainage firm can measure sludge and inspect the tank if you need figures. This survey does not have them. Tell a lender the crust was a visual note, no ticket was seen and volume was not measured. Do not convert a cover glance into a statement that the tank has a known period of capacity left.
What should you ask your surveyor?
- Was the crust only seen, with no sludge depth measured?
- Is there no emptying ticket in the papers?
- Did the cover glance fail to measure volume?
What are the typical next steps?
- Record crust, missing ticket and unmeasured volume separately.
- Ask the solicitor for emptying tickets and any permit.
- Use a drainage firm if sludge depth must be measured.
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
Is a septic tank emptied on the same basis as a cesspool?
They are different. A cesspool holds sewage and must be emptied because it does not treat and discharge in the same way. A septic tank still needs desludging, but the crust and a missing ticket do not set the interval. The survey did not measure volume. Ask the contractor's tickets what has actually been done.
Does a wet patch downhill prove the tank is overflowing?
Not by this visit. A wet patch can be land drainage, a spring or a leak, and the survey did not test the outlet or measure the tank. No emptying ticket was available to date the last removal. Tell the solicitor the patch, if noted, is not a volume. A drainage firm would have to trace it.