My septic tank discharges into a ditch. Is this ok?

Regulatory | By Sam Warren

Many people are not sure what type of off mains drainage system they have. After all, unless you are something of an expert, it can be pretty tricky working it out since they are tucked neatly away underground. And if the system is working as it should do, most people are happy to leave it well alone.

There are three main different types of off mains drainage tank - a septic tank, a sewage treatment plant and a cesspit. Septic tanks and sewage treatment plants will then have some form of pipe which runs from the tank, and which typically takes some of the waste water and safely discharges it either into the ground, or to a local watercourse or ditch. If you have a septic tank which discharges into a ditch, is this ok?

The waste from most septic tanks flows to a soakaway system, also known as a drainage field. Let me explain quickly what a soakaway system or drainage field does. It is usually a network of perforated or slotted pipes which allow waste water from the septic tank to percolate through and into the surrounding sub soils. This provides a form of treatment of the waste water, which can then safely pass into the soil without causing a pollution. If your septic tank doesn't have a soakaway system, the waste water will instead flow through a sealed pipe and empty straight into a ditch or a local water course.

So, is it a problem if your septic tank discharges into a ditch?

In a word, yes. The problem is that the waste water that comes from septic tanks is no longer considered safe to pass straight into local watercourses or ditches without any form of treatment. A soakaway system or drainage field provides a form of treatment, so the waste water doesn't cause a pollution. But a sealed pipe will literally take the untreated waste straight to its destination, and into the local environment where it can cause real issues.

Septic tanks don't actually provide any treatment of the waste that flows into them. All that happens is that the waste settles into three different layers, and the middle layer of separated waste water is what passes through into the soakaway system. Compare this to a sewage treatment plant, which does provide treatment of the waste, meaning that what leaves the tank is cleaner and able to pass straight into a ditch or watercourse without any issues (assuming that its working as it should be).

You are no longer allowed to have a septic tank which discharges into a ditch or a local watercourse. If you have a septic tank, it must connect to a soakaway system which is appropriate to your property and the ground conditions. In recent years, you were only made to take action to remedy this if your system was found to be causing a pollution. But new legislation due to come into force in 2020 will mean that anyone with a septic tank which discharges into a ditch MUST upgrade their system. The legislation also states that if you are selling your property before 2020, you have a duty to upgrade the system prior to selling it.

How do I know if my septic tank discharges to a ditch?

It's not easy to tell, because the system is underground. If a ditch runs close to your property, you can take a look to see if you can spot the end of the outlet pipe which would run from your septic tank, and which is often visible.

You can also take a look in the manhole after your septic tank, which is usually a distribution chamber. If you see a number of different entrances to pipes, this more than likely indicates that your septic tank connects to a soakaway system instead. Please be careful though if you do take a look, manhole covers can be very heavy to lift!

The best way to know for sure is for a local specialist to investigate and confirm this for you. If you're due to have your tank emptied, why not get in touch and arrange a Septic Tank Health Check with one of our team of engineers? They can confirm the type of system you have in place, as well as checking the condition of the tank and the pipe work. Call our team today to find out more on 0800 028 9903 or send us a message here.

What are my options if my septic tank discharges into a ditch?

You have two options:

  1. Replace the pipe which runs to the ditch or watercourse with a soakaway system or drainage field. You'll need percolation tests to be undertaken first. These are really important because they will tell you whether the ground at your property is appropriate - and if so, what type of soakaway system is relevant and what size it needs to be.
  2. Replace the septic tank with a sewage treatment plant.

Cost-wise, it's not possible to say which of the above options would be the most cost effective. This is because so much rests on the ground conditions at your property as to what size of soakaway system you might need - and therefore how much it might cost to install. If you need a large soakaway system, you may find that a sewage treatment plant is more cost effective. Of course, there are a range of prices for sewage treatment plants, so it's worth getting advice on the right one for your property.

We know that the world of septic tank regulations can be a little mind boggling, so we have produced a quick and easy guide for property owners here.

So, if your septic tank discharges into a ditch, you'll need to take action. Contact our friendly team today for advice and guidance.

0800 028 9903