Should I buy a house with private drainage?
What private drainage means for your costs, responsibilities and compliance before you buy.
Key takeaways
- Yes, as long as you know exactly what condition the private drainage system is in before you buy.
- Private drainage means a septic tank feeding a drainage field, a treatment plant feeding a drainage field or (where the rules allow) a watercourse, or a cesspit that holds the waste.
- Mains users pay sewerage rates of around £400 a year, while a septic tank needs emptying about once a year for £120 to £150.
- A cesspit needs emptying more often than a septic tank, so it costs more to run.
- You are responsible for the whole private system, including repairs and discharge issues, even where it sits on someone else's land.
- Private drainage must follow the general binding rules, which aim to stop leaking tanks polluting the environment.
- Get a homebuyer drainage survey before you buy, and read up on the regulations that will apply to you.
There are many upsides to living somewhere more rural. All that lovely fresh air and bracing walks through the fields. But there are other things to think about when contemplating a move to the country, and it’s not necessarily something you’d want to dwell on for too long. Drainage is a crucial part of any household. No one likes to talk about it, but everybody needs it! And drainage for rural properties is often very different from what you might be used to if you’ve been living nearer to a town connected to mains. So, should you buy a house with private drainage?

A home with private drainage looks after its own wastewater through a septic tank or treatment plant and a soakaway, rather than a mains connection. Knowing which system a property has, and the running costs that come with it, is the first thing to weigh up before you buy.
What are the main differences between living somewhere with private drainage versus being connected to a main drain?
There are different types of private drainage (or off-mains drainage) systems, including those that require a drainage field. There will typically be a tank such as a septic tank or sewage treatment plant, which will run to a soakaway system or, for a treatment plant where the rules allow, to a local watercourse. If the property has a cesspit, this is basically a holding tank for the waste, so there will be no pipework running through it. If your property connects to a main drain, there will be a sewer pipe which takes the waste from your property to the nearest main drain. The main differences between private drainage or being connected to a main drain are:
The financials
If you connect to a main drain, you will pay sewerage rates to the local Water and Sewerage Company. This can vary but is typically around £400 per year. If you have private drainage such as a septic tank, it will need to be emptied regularly, usually annually. Again, the price for a tank empty can vary, but on average you’re looking at £120-£150 for a private drainage system. A cesspit will need more regular emptying than a septic tank and therefore is a lot more costly to operate, however there are relatively few properties with cesspits.
Your responsibilities
With a property connected to a main drain, once the pipe passes beyond the boundary of your property, it becomes the responsibility of the water company you are paying rates to. With private drainage such as a septic tank, you are responsible for the whole drainage system, including any discharge issues, even if it’s on someone else’s land. So, if it needs upgrading or repairing, the costs will fall to you, and you might find they can leave quite a dent in your bank balance, especially with a private drainage system. The number one rule? Don’t buy a property with private drainage, unless you know exactly what condition it’s in. A homebuyer drainage survey will tell you all you need to know about wastewater management, and help to protect you against any unpleasant surprises.
Legislation and regulations
The world of private drainage is surrounded by various rules and regulations that you must abide by if your property has one. After all, a leaking septic tank or cesspit can allow raw sewage to escape into the local environment, and that’s no good for anyone according to the environment agency. So the general binding rules are there to try to prevent pollution, or to nip it in the bud quickly if it happens. Don’t worry, here at UKDP we have produced an easy-to-understand guide on private drainage systems. Guide to Septic Tank Regulations, which explains how they might affect you.
There are some big differences between owning a property connected to a main drain, and one with private drainage such as a septic tank or cesspit. But it doesn’t have to be stressful or confusing with the UKDP team on your side. Send us a message hereor call our friendly team on 0800 028 9903 to find out how we can help you if you are buying a property with private drainage.
Frequently Asked Questions
Is a house with private drainage harder to sell later?
No. Plenty of rural homes change hands with a septic tank or treatment plant. As long as the system is compliant and in good order, it's a normal part of the sale. Problems only arise when a non-compliant system is left to the last minute.
Can I connect a house with private drainage to the mains sewer instead?
Sometimes, if a public sewer is within about 30 metres and the water company agrees. It isn't always possible or cheap, so treat a mains connection as a bonus rather than a given when you buy.
What happens if the private drainage isn't compliant when I buy?
You'd take on the cost of putting it right, which for a new drainage field or treatment plant can run to £10,000 or more. That's why a drainage survey before you commit matters; if it finds a problem you can ask the seller to fix it or adjust the price.
What's the difference between private drainage and a private sewer?
They point to the same thing: drainage that isn't connected to the public network, usually a septic tank, treatment plant or cesspit. ‘Private sewer’ is just the conveyancing term for it.
How do I find out what drainage a property has before I buy?
The seller must tell you in writing under the binding rules, and the property's information form and title deeds usually note it. A drainage survey confirms the type and condition once you're serious.
About the author
Sam Warren
UKDP co-founder
Sam Warren co-founded UKDP with James Warren in 2009 as an off-mains drainage specialist.
Need help with your septic tank or drainage?
Reach out to us on 0800 028 9903. Our team are here to talk Monday to Friday 9am to 5pm.
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