CSG’s guide to buying a house with a septic tank

05 August 2024 by CSG

If you purchase a property with an off-mains drainage system, you may not be aware of exactly how that system works.

There are multiple different types of off-mains drainage system that your property might have, and each of them needs to be maintained in a different way.

The 3 most common types of system are:

1. A Septic Tank (an underground tank where the solids sink to the bottom and the liquid flows out and soaks through the ground)

2. A Sewage Treatment Plant or Packaged Treatment Plant (also known as a ‘package treatment plant’ – a system that treats the liquid so it’s clean enough to go into the ground or a surface water)

3. A Cesspit (a watertight storage tank which holds sewage and is stored underground in a pit.)

As a homebuyer with an off-mains sewage system, you are responsible for making sure that your property’s off mains drainage system doesn’t pollute or harm the environment. There are regulations in place that you must adhere to, if you don’t and your system pollutes the environment you could be fined.

Owners of an off-mains sewage system don’t pay charges to water or sewage companies as they aren’t connected to a main sewer. You must get the sludge that builds up in your sewage tank or sewage treatment plant removed (desludged) at least once a year or in line with the manufacturer’s instructions. The company you use to dispose of your waste sludge must be a registered waste carrier, such as CSG!

If you have a septic tank, it can only discharge to the ground via a drainage field. Discharging to a watercourse is not permitted. Drainage fields must be a minimum of 10m from a watercourse, 50m from a water abstraction point and 15m from a building.

They should also be sufficiently far away enough from any other drainage fields, mounds or soakaways so that the soakage capacity of the ground is not exceeded.

If you have a sewage treatment plant, you should also have this regularly maintained in line with the manufacturer’s instructions. Anyone who carries out maintenance on your system must be competent. Competent people include those on British Water’s list of accredited service engineers. We have the largest number of British Water accredited engineers of any company in the UK!

What to look out for or be aware of before moving

Before purchasing a property with an off mains drainage system, there are certain questions that you should ask. These include:

1. Has the tank been regularly emptied by the current owners?

2. How much does the tank ‘typically’ cost to empty?

3. Is the tank shared with any other properties? If so, what agreement is in place around emptying, maintenance, and repair? What is the current owner’s relationship with the property owners?

4. Is any of the drainage system located outside the properties boundary? If so, what rights exist for access for emptying, maintenance, repair or replace?

5. If the property has a drainage field, is there enough space for a replacement one if it fails?

6. What is the condition of the tank and pipework?

If you are unable to get this information from the current owner, it’s recommended that you speak to your solicitor or commission a report from a specialist. These can be called a home buyers drainage survey.

The home buyer’s drainage survey

Homebuyers are typically required to undergo a comprehensive house survey as an essential step in the purchasing process. Many mortgage lenders and insurers demand a thorough surveyor’s report before they become involved in the transaction.

The drainage system of a property is frequently neglected, partly due to surveyors lacking the necessary equipment and expertise to conduct thorough drain surveys for assessing their condition, and partly because home buyers tend to overlook drainage-related risks. However, undetected drainage issues can result in significant problems, leading to unpleasant surprises and costly repairs if not promptly addressed.

This is why we recommend that anybody looking to buy a property with an off mains drainage system should commission a home buyers drain survey. This survey will thoroughly inspect the tank and show a diagram of the drainage system layout.

You will also receive confirmation that the tank is of adequate size for the property and a full report on the tank’s conditions. Guidance will also be provided to make sure the tank is compliant with the general binding rules.

These surveys can cost between £500 to £1000 depending on additional features and locations. Considering a replacement system can cost you upwards of £10,000, we think it’s worthwhile to give you piece of mind!

How can I tell if something is going wrong?

Maintaining a healthy system is crucial for you and your family’s well-being and will allow you to enjoy your new property to its fullest. Below are key signs to watch out for that may indicate the system has a problem:

1. Foul odours

2. Slow drains

3. Pooling water or unexplained puddles

4. Particularly lush vegetation growth above the tank

5. Sewage backing up

If you notice any of these issues it is essential that you address the problem. If you have yet to move into the property, you can discuss options to reduce the property cost for the cost of repairs.

If you have already moved in and discovered the issues afterwards, the sooner you fix the problem the better it will be.

To stop anything going wrong with your system in the future, our Septic Tank Care – The Do’s & Don’ts blog has some of our best tips on how to keep your sewage system in tip top condition.

What about the environment?

The problems above can also be tied to your system polluting the environment. If your tank or system is leaking, then excess nutrients are also being released. For example, the lush garden growth that can indicate a leak. The reason for the extra growth is the excessive nutrients being released into the environment.

If these were to contaminate a waterway, eutrophication can take place rendering the waterway uninhabitable for wildlife. This will harm the environment, damage local economies and can even pollute drinking water.

Another problem that can be caused by the improper care of your sewage system is that it can foster the spread of disease. These include nasty parasites and infections such as bacterial, viral and parasitic infections.

There are also other things in the waste that are known to have a negative affect on the environment if they leak out, such as medicines and cleaning products.

Conservation organisations can also help to reduce the negative effects that septic tanks can have on the environment. These groups can help to educate off-mains homeowners to improve their practices. A great example would be the Hampshire & Isle of Wight Wildlife Trust. They have launched the Septic Smart project to help support their Watercress and Winterbournes Scheme. The project hopes to spread awareness of poor septic system management and the negative effects this can have on the UK chalk streams.

Want to know more about the effects that neglecting your sewage system can have on the environment? Read our Habitat Protection and Your Septic Tank blog here!

How CSG can help – regular servicing and collections

We deliver domestic waste services to householders every day, specialising in the collection and treatment of household sewage.

When your septic tank, cesspit or sewage treatment plant needs emptying, you can rely on our friendly team of drivers to attend to the job quickly and carefully.

We also offer you dependable, low-cost maintenance and repair services, including blockage removal, sewage system servicing or the reassurance of 24 Hour Emergency Cover when things go wrong.

Want to know more? Contact us today by clicking here or give us a call on 0800 011 6600.