The best questions to ask when buying a house with a septic tank

Sam Warren's Photo
Written by Sam Warren

You're making that move to the countryside. The picture postcard cottage you've had your eye on for a while now is finally going to be yours, and you can't wait. All that fresh country air, tweeting birds and......the smell of a failing septic tank? Now, that was never part of the plan! Don't let nasty niffs spoil your new home, especially when the cost of dealing with septic tank problems and replacing a damaged drainage system can often exceed £10,000. If you're buying a rural property, the chances are it will have its own self contained drainage system which won't connect to mains drainage. Read on to the find out the best questions to ask when buying a house with a septic tank.

How does a septic tank work?

It might not be your life's ambition to know how a septic tank works, but if you're buying a house with a septic tank, it will probably pay to understand it a little! Here's our video explaining the basics (don't worry, there's nothing graphic in there, you can carry on eating your lunch):

Video how a septic tank works

How Your Septic Tank Works

It’s hard to know what goes on underground, out of sight. This video explains everything to give you a better understanding of how a septic tank works.

What type of drainage system does the property have?

It will have some sort of tank - either a septic tank, cesspit or sewage treatment plant. What type of tank the property has is important because it will dictate the level of maintenance it will need, and therefore the amount it's going to cost you to look after. For example, septic tanks and sewage treatment plants typically need to be emptied around once a year. A cesspit may need emptying 4-8 times a year.

Once you know what type of tank it has, you'll need to know where the waste goes when it leaves the tank. Unless it is a cesspit, which is literally a holding tank with no outlet - hence why it needs emptying so often. Septic tanks and sewage treatment plants will go to one of two places:

  1. A soakaway system or drainage field - this is typically a network of perforated or slotted pipes which allow waste water from the tank to safely percolate into the soil around them.
  2. A solid pipe discharging to a local watercourse, such as a ditch or local stream.

Will the current system comply with the 2020 regulations?

This is a crucial question, regulations are in force which will affect property sales before 2020 (and beyond, as it will be a permanent requirement for drainage systems to comply). The key thing to be aware of is that it is no longer legal for a septic tank to discharge straight to a watercourse. A septic tank will only be able to discharge to a drainage field (or an alternative soakaway system if the Environment Agency has given permission). This is because a septic tank doesn't provide any real treatment of the waste that goes into it. A soakaway system or drainage field provides a form of treatment of the waste water which makes it safe to pass into the soil. There is no treatment of the waste water which passes through a solid pipe straight to a watercourse, and it's now considered that this carries too high a risk of pollution. If you'd like to know more about septic tank regulations, you can check out our Guide to Off Mains Drainage Regulations here.

A sewage treatment plant provides a level of treatment of the waste water, which is considered safe to discharge to a watercourse. However, if the property you are buying has a septic tank discharging to a watercourse, the owner will need to take action to make the system compliant before selling the property. There are usually 2 options:

  1. Replace the septic tank with a sewage treatment plant
  2. Replace the solid pipe to the watercourse with a drainage field

If you're unsure about this, call our team for advice today on 0800 028 9903, or contact us. We regularly undertake homebuyer drainage surveys, and we specialise in off mains drainage, so we can help with all aspects from identifying what type of system is at the property, to whether it will be compliant with the current regulations.

Is the septic tank shared with anyone else?

Most septic tanks are individual to the property they connect to, but some are shared by two or more properties. If this is the case at the property you are buying, you will want to know what the arrangements are for regular emptying, who arranges it and how are payments sorted out? Also, what would happen if the septic tank became damaged, how would everyone agree next steps? Where is the septic tank located? If it is on your property, what rights of access do the other properties sharing the septic tank have? You can check out our Guide to Shared Septic Tanks here.

Is the septic tank and soakaway system within the property's boundary?

It is surprisingly common for part of a property's drainage system to be situated on someone else's land. It's not necessarily a problem, but you'll need to know more about the set up. Whose land is it on? What is the relationship like with them? What are your rights of access to repair or replace the part of the system not on your property?

Similarly, if you are buying a property with someone else's drainage system within your boundary, you will want to know exactly what that entails, and what rights of access the neighbour has. What would happen if the system failed and couldn't be replaced like for like?

When was the septic tank installed?

As we all know, age isn't always a bad thing. The same is true of septic tanks. You'd be surprised how long a well constructed and looked after septic tank can last - we've seen tanks well in excess of 50 years old which are still working as they should be. So don't be put off if the current drainage system is a little on the mature side, you just need to get it properly checked over to make sure it is still in good serviceable condition, and not showing any signs of deterioration.

How well has the current septic tank been maintained?

Most septic tanks will need to be emptied annually. Now, this can vary based on the size of the tank and the number of people using it, but that's a good starting point. You will want to know that this has happened regularly, because not doing so can cause problems with the soakaway system or drainage field which may not yet be evident. You see, often problems underground can take time to manifest themselves above ground, so all seeming well on the surface doesn't mean that there isn't trouble brewing.

Have there been any recent inspections of the septic tank?

Septic tanks can be damaged in all sorts of different ways - from tree roots growing through the walls, to splits in the walls of the tank, to broken dip pipes or baffles. This damage often won't be evident, and it may not yet be causing any problems above ground. The tank will need a thorough inspection to assess the condition of the walls, and ideally to check whether the drainage field or soakaway system is working as it should be.

Please bear in mind that most standard property surveys will not look at the drainage system in any kind of detail. The surveyor may lift a manhole and comment that things seem to be flowing, but generally they will recommend that you get a specialist company to carry out a full survey. Here at UKDP we get a large number of calls from people who have recently bought a new property and are already experiencing problems. When we ask the question about whether they have had a survey undertaken, there is often a rustling of paperwork before the caller reads out the line out about needing a specialist survey. We ask, did one get done? The answer is nearly always no.

Don't leave anything to chance, because getting it wrong can be very costly. We understand that once you've set your heart on your potential new home, the last thing you want to do is to find problems that might need to be sorted out. But don't let your heart rule your head, as many of our glum sounding callers did! Our specialist team can undertake a full survey of the drainage system, providing you with a full report to give you peace of mind and also giving you the chance to resolve any problems before it's too late. Call us today to find out more on 0800 028 9903 or contact us.

Don't let buying a house with a septic tank get messy

The list above is a belt and braces approach to buying a property with a septic tank, please don't let it put you off. Many people take a much more carefree approach to property purchases, but the risk is that they are left exposed if a problem appears.

Here at UKDP we specialise in septic tanks and all other types of off mains drainage systems, and our team of engineers are very experienced in carrying out thorough investigations before you buy a property. With the UKDP team on your side, you can be confident in the decisions you are making.

Call us today on 0800 028 9903 to find out more about how we can help.

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Sam Warren's Photo
Written by Sam Warren

Sam's career prior to UKDP was spent in the marketing and service industries, so she is focused on making sure we look after our customers – and getting the UKDP message out there! Sam has overall responsibility for business operations and for delivering the best customer service we can.

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