What is a soakaway and how does it work?
A soakaway is an underground pit that collects rainwater, usually from roofs and paths. It holds the water and lets it seep slowly into the ground. It is often filled with stone or fitted with a plastic crate.
It works only if the soil lets water through. Therefore, a soakaway suits some sites and not others. Clay soil drains slowly and may not suit one.
Why soakaways fail
Silt, leaves and debris can clog the soakaway. The pit then fills and cannot empty. Roots can also block the stone.
Poor design is another cause, because a small pit cannot cope with heavy rain. Soil type matters too. A high water table can stop water from draining at all.
Testing whether your soakaway is failing
Watch it during and after heavy rain. If water backs up in the gully, the soakaway may be full. Wet ground over the pit is another sign.
Check the inlet pipe and any chamber. Clear leaves from gullies first, because blockages upstream can cause the same signs.
Can a soakaway be repaired?
Sometimes, yes, although it depends on why it failed. If silt has clogged it, cleaning may help. Replacing the stone or crate can restore it.
If the soil no longer drains, repair may not work. A camera check on the pipe shows whether the fault is in the pipe or in the pit.
Planning a replacement soakaway
A new soakaway needs the right size and location, since a poor site fails fast. It must sit well away from buildings and boundaries. Soil tests show how well the ground drains.
Building rules may apply. Check with your local building control team. If you also have a septic tank, see our septic tank maintenance guide, because the two systems work differently.
SUDS alternatives to soakaways
Sustainable drainage options include permeable paving and water butts. Rain gardens and swales can also help. These slow water and let it soak in or evaporate.
Ask a qualified designer which suits your site. Because soil and space differ, there is no single answer.
Before any work, ask your local council whether you need permission. Check where the overflow will go, because water must not run onto neighbouring land. Keep records of the design and the date of the work, since they help if you sell the property.
Related guides and local help
If you want to know more, read 10 Hidden Plumbing Problems in Victorian Homes to Look For. You can also read Septic Tank Maintenance: A Complete Guide for UK Homeowners and Foul Drain vs Surface Water Drain: What Goes Where?, because they cover closely related problems.
These guides help too: 7 Signs Your Restaurant Drain Needs a Maintenance Contract, Why Drains Smell Worse in Summer and How to Stop It, 5 Warning Signs of Pitch Fibre Pipe Failure to Watch For, CCTV Drain Survey: What to Expect and When You Need One and Manhole Cover Replacement: Types, Load Ratings and Costs. Each one explains a related topic in plain English.
Need help near you? Read our drain jetting page first, or see Drain Jetting in Bletchley and Drain Jetting in Blyth. You can also see Blocked Drains in Crossgates, since every service page has a free quote form. We pass each request to a local drainage engineer.
