---
title: What should a filling station do with mixed fuel tank sludge?
url: https://cityfuel.services/questions/what-should-a-filling-station-do-with-mixed-fuel-tank-sludge/
publisher: City Fuel Services Ltd
---

# What should a filling station do with mixed fuel tank sludge?

In brief

A filling station that finds sludge in mixed fuel tanks should stop using the fuel, keep it contained and away from drains, and have it assessed for collection. Sludge is drawn into the fuel lines when tanks run low or are stirred up by a delivery, blocking filters and starving engines, boilers and generators of fuel. Call [07950 582635](tel:+447950582635) or [send an enquiry](https://cityfuel.services/enquiry/).

## Sludge in mixed fuel tanks at filling stations

At filling stations, forecourt crossovers, water in underground tanks, tank cleaning residues, fuel drained from customers' misfuelled vehicles, and fuel left when tanks are decommissioned. Sludge is the thick layer that collects at the bottom of fuel tanks over years: water, microbial growth, rust, dirt and degraded fuel settling together.

## Collecting mixed fuel tank sludge from filling stations

Underground storage tanks, interceptors, and drums from tank cleaning. As needed after incidents, and planned around tank cleaning and maintenance.

## Rules at filling stations

Filling stations storing petrol need a petroleum storage certificate from the petroleum enforcement authority, and follow DSEAR and the industry's filling station guidance, known as the Blue Book.

## Is mixed fuel tank sludge still worth collecting?

Mostly no.

## How City Fuel Services handles waste mixed fuel

City Fuel Services buys, collects and handles waste mixed fuel for businesses, public bodies, farms and households. Describe the load and we come back with terms before booking the collection.

## Terms used in this answer

**Diesel bug**: Bacteria and fungi that grow where water meets diesel in a tank. They form slime and sludge that block filters.
**Bund**: A wall, tray or outer case around a fuel container that holds any leak. For oil and fuel stored at a business, bunds for tanks, bowsers and IBCs are sized at 110% of the container.

**Key facts**

| Problem | Sludge in Mixed fuel |
| --- | --- |
| Sector | Filling stations |
| Fuel | [Mixed fuel](https://cityfuel.services/fuels/mixed-fuels/) |
| Also called | mixed petrol and diesel, cross-contaminated fuel, petroleum distillates |
| Waste code | 13 07 03* (other fuels (including mixtures)) |

## Related questions

- [What should I do with mixed fuel tank sludge?](https://cityfuel.services/questions/what-should-i-do-with-mixed-fuel-tank-sludge/)
- [How does a filling station dispose of waste mixed fuel?](https://cityfuel.services/questions/how-does-a-filling-station-dispose-of-waste-mixed-fuel/)
- [What happens if sludge builds up in mixed fuel tanks?](https://cityfuel.services/questions/what-happens-if-sludge-builds-up-in-mixed-fuel-tanks/)
- [What should a filling station do with mixed fuel contaminated with water?](https://cityfuel.services/questions/what-should-a-filling-station-do-with-mixed-fuel-contaminated-with-water/)
- [What should a filling station do with mixed fuel contaminated with sediment?](https://cityfuel.services/questions/what-should-a-filling-station-do-with-mixed-fuel-contaminated-with-sediment/)

**Official guidance:** [GOV.UK: hazardous waste](https://www.gov.uk/dispose-hazardous-waste).

---
City Fuel Services Ltd, Fairfield Road, Droylsden, Manchester M43 6AX. Call 07950 582635 or send an enquiry at https://cityfuel.services/enquiry/.