Flood risk
What did the visit record about a swale, about the bottom of the garden, and about whether it is a soakaway or a flood route?
The visit recorded a swale at the bottom of the garden, and it did not decide whether that swale is a soakaway or a flood route. A swale is a shallow planted channel. The surveyor could see the dip and where it sits. They did not test how water soaks in, did not follow the channel off the site, and did not measure flood depth. The note is the feature that was visible. GOV.UK's long-term flood-risk check is a separate product. This inspection has not carried it out and has not labelled the swale.
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 swale can be designed to hold runoff and let it soak, or it can be the low route water takes when the garden floods, or it can be both. The bottom of the garden is where this one was seen, which is a place water will reach if the ground falls that way. Looking at grass in a hollow does not show the soil's soakage and does not show whether the hollow discharges into a neighbour's land or a ditch. The visit recorded the shape and the position.
Ask the solicitor whether the swale is on this title and whether any design calls it a soakaway or an overflow route. A drainage firm can test soakage if you need that answer. The survey has not done so. Tell them the home survey also did not measure flood depth. Use the separate long-term flood-risk check if you want the area information GOV.UK publishes, and do not expect this report to be that check. Keep the visible hollow and the untested function apart.
What should you ask your surveyor?
- Did the swale hold water on the day, or was it dry?
- Could you see an outlet from the hollow, or did it appear closed?
- Does the ground fall toward the bottom of the garden from the house?
What are the typical next steps?
- Treat the swale as a seen hollow, not as a proved soakaway or flood route.
- Ask the solicitor how the feature sits on the title and on any design.
- Use the long-term flood-risk check separately if you want area flood information.
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 dry swale evidence the garden does not flood?
No. Dry grass in a hollow shows the day of the visit. It does not show what happens in prolonged rain, and the survey did not measure flood depth. The swale was recorded at the bottom of the garden. Its role as soakaway or flood route was not decided. A single dry inspection does not clear the low ground.
Should the swale be filled in to gain lawn?
Not on this note. Filling a hollow that may be a soakaway or a flood route could move water toward the house or a neighbour, and the survey has not decided which job the swale does. It only recorded what was visible. Ask the solicitor and a drainage firm before any levels are changed. The report has not specified filling it.