Drain misconnections: How they affect our environment

As a property owner – whether domestic or commercial – it’s important to consider how you can minimise your impact on the environment, especially when your drainage could be causing serious harm to the environment and be putting yu at risk of a hefty penalty.

What is a drain misconnection?

The majority of properties in the UK are connected to two sewers – a foul water sewer and a surface water sewer. Waste water from appliances such as a washing machine, showers and toilets are discharged into a foul water sewer and later treated at a wastewater treatment plant, before being released into rivers and streams. Whereas water from drain pipes and runoffs is discharged into a surface water sewer, which is then directly released into streams, rivers or the sea without being treated.

A drain misconnection is essentially when plumbing is accidently discharged into the wrong sewer; for example, if a dishwasher was plumbed to a surface water sewer. The potential consequences of a misconnection that is left unaddressed can be disastrous for the environment, public health and wildlife. According to the Department for Environment, Food and Rural Affairs (DEFRA), there is still an estimated 150,000 to 500,000 UK homes with some sort of drain misconnection.

What are the effects of a drain misconnection?

There is a number of consequences to the environment and wildlife if a misconnection is left unaddressed.

• Chemicals
• Human waste
• Plastic waste

Household products such as bleach, washing up liquid, and even items like shampoo and conditioner, contain a whole host of chemicals that can be incredibly harmful to the environment and wildlife, especially when combined with one another. Chemicals often found in cleaning products such as chlorine, ammonium, and zinc can be toxic to animals and plants found in rivers and the ocean.

When a toilet is plumbed to a surface water sewer, it means that human waste is directly discharged into rivers and streams. This is can affect both public health and the environment in numerous ways.

Firstly, when sewage is discharged into an open source of water, it begins to decompose and uses up oxygen from the surrounding water. If the sewerage amount is high, the amount of oxygen available for the surrounding fish, plants and aquatic animals may not be enough, posing a threat to their lives.

Secondly, sewerage and general human waste contains bacteria that has the potential to cause diseases and viruses. This creates a risk to public health, especially swimmers and those eating contaminated fish.

According to the Marine Conservation Society, 8.5% of the litter found on the UK’s beaches comes from waste that is flushed. Most domestic toilets will be connected to the correct sewer, and therefore those items are still managing to bypass the filtering process at treatment plants. In the instance of a misconnection, all items flushed would end up in the environment – releasing harmful chemicals into rivers and the ocean, and threatening wildlife who often mistake small pieces of plastic for food.

How to identify a drain misconnection?

A drain misconnection is the responsibility of the property owner. There can be substantial punishments for not resolving a misconnection on a property and causing significant damage to the environment. In some cases, failing to address a misconnection can result in a fine of up to £50,000 or imprisonment for up to 12 months.

A misconnection is often found in older properties or is caused by dodgy plumbing. You can find out more about misconnections, how to identify them and the regulations around drainage and sewerage in UKDN’s whitepaper – Are your drains breaking the law?