Non-mains Drainage Upgrades

The non-mains drainage upgrade scheme is designed to unlock homes affected by nutrient neutrality and fight the effects of phosphorus pollution.

We’re on the lookout for septic tanks and package treatment plants (PTPs) that can be upgraded to reduce the amount of phosphorus released into the environment. If your system is chosen for the scheme, we’ll replace it free of charge.

A septic tank treats waste by decomposing solids at the bottom and discharging water into the ground, with solids removed later on.

PTPs are modern, efficient septic tanks. They need an electrical connection, but they take up less space, require less emptying, and are more effective at removing nutrients. They can discharge into soakaways, surface water, groundwater or drainage fields. PTPs must be maintained according to the manufacturer’s guidelines.

New developments increase the levels of nutrients like phosphorus in watercourses, causing pollution, algal growth and harm to aquatic species. Nutrient Neutrality (NN) works to offset these effects and balance levels of phosphorus.

Before developers can get planning approval, they must find a way to offset the impacts of their development. This means that many new homes, including affordable housing, get delayed in the planning system while solutions are found.

NN restrictions are in place in four Habitat Sites that have been damaged by phosphorus: River Eden SAC, River Derwent and Bassenthwaite Lake SAC, River Kent SAC and Esthwaite Water Ramsar.

Cumbria NN have appointed two contractors to deliver non-mains drainage upgrades, including Package Treatment Plant (PTP) replacement across the nutrient neutrality catchments in Cumbria:

• Burrow Environmental
• Our Rivers (a joint venture between Nutrient Neutral and Hutchinson Environmental Services)

The scheme is designed to support developers in meeting nutrient mitigation requirements, helping unlock stalled planning applications while improving water quality.

1. Site selection: The contractors will prioritise properties where replacing the existing tanks will deliver the greatest environmental benefit.
2. Property survey & phosphorus calculations: The contractors will arrange a property survey and complete calculations to measure the phosphorus savings. They will guide you through the physical and legal needs of your tank.
3. Reporting: The contractor will produce a Technical Mitigation Report, which will be sent to Cumbria NN for approval.
4. Legal agreement: Once approved, you will enter into a legal agreement to secure phosphorus savings for the wider scheme.
5. Installation: Your upgraded tank will be upgraded free of charge, and the Cumbria NN will receive the mitigation needed for other developments.

To register your interest in the scheme, you can contact the appointed contractors directly:

• Burrow Environmental
• Our Rivers

If the discharge from your existing septic tank/PTP meets the definition of a ‘small-scale discharge’, it may still be eligible.

Eligibility depends on how much water is discharged from your system. To find out discharge rates for typical tanks and PTPs linked to domestic properties, use this simple online calculator.

There are two types of small-scale discharge: to the ground and to surface water.

Small-scale discharges to the ground

This includes systems that discharge two cubic metres of water or less per day.

For detailed information, see General Binding Rules: Small sewerage discharge to the ground.

In addition, existing septic tanks and PTPs that meet the General Binding Rules can be accepted if they meet any one of the following criteria:

• The drainage field is less than 50m from the designated site boundary

• The drainage field is less than 40m from any surface water feature – for example, a ditch, a drain or a watercourse

• The drainage field is in an area with a slope greater than 15%

• The drainage field is in an area where the high water table groundwater depth is less than 2m below the surface at all times

• The drainage field is in flood zone 2 or 3

• The discharge to ground is less than 200m from any other discharge to ground.

If you’re not sure whether your system meets the criteria, we’ll work with you to identify whether it does (depending on location and available funding).

Small-scale discharges to surface water

This covers systems that discharge five cubic metres or less per day. For detailed information, see General Binding Rules: Small sewerage discharge to surface water.

Current small-scale discharges via a PTP to surface water are already discharging nutrients directly into a watercourse, so they do not have to meet any criteria to be eligible for an upgrade.

However, if a septic tank is discharging to surface water, legally speaking it should have been upgraded by 2020. Therefore, it will only be able to generate credits over and above a standard legal PTP level of discharge.

If you’re not sure whether your system meets the criteria, we’ll work with you to identify whether it does (depending on location and available funding).

First, use our online maps to see whether your site is within an affected catchment area. Then contact either/both of our contractors for further details:

• Burrow Environmental
• Our Rivers