Dye Testing

When drainage problems are recurring, intermittent, or happening across a large commercial site, dye testing is one of the fastest ways to prove what connects where.

ICE Drainage provides dye testing for drainage investigations across London and the Home Counties, supporting hospitality venues, commercial kitchens, facilities management teams, property managers, schools, retail sites, and multi-tenant buildings.

Whether you need to confirm connectivity, investigate a suspected misconnection, or trace the source of odours and blockages, we carry out dye testing safely and with minimal disruption, then give you clear findings and next steps.

What is dye testing?

Dye testing, sometimes called dye tracing, is an investigation method where we introduce a non-toxic coloured dye into a specific drain run, such as a sink, gully, WC, floor drain, or kitchen waste line, and then observe where that dye turns up in the drainage network.

This lets us confirm which appliance or area connects to which inspection chamber, the direction water is flowing through the system, whether a drain is connected incorrectly, and whether multiple areas are feeding into the same problem point.

It's a simple idea, but on complex commercial sites it can save days of guesswork.

When dye testing is useful

Dye testing is particularly effective when drainage drawings are missing, outdated, or unreliable, when you're dealing with recurring blockages and can't prove the source, when there's a suspected misconnection between foul and surface water systems, when odours are present but the source isn't clear, when multiple tenants share a drainage network, or when you're planning remedial work and need evidence to make sure you're fixing the right thing.

For hospitality sites, it's commonly used to trace kitchen lines and confirm where grease-heavy flows are entering the system.

Common problems dye testing helps identify

Dye testing is often used to confirm or rule out misconnections between foul and surface water systems, kitchen waste lines discharging into an unsuitable run, multiple units feeding into the same chamber without anyone realising, incorrect tie-ins after refurbishments or fit-outs, and unexpected connectivity between buildings or site areas. It can also help confirm whether a reported issue is coming from inside the building or from further downstream.

Our dye testing process

We keep dye testing practical, evidence-led, and safe on site.

1) Define the investigation objective

We confirm what you need to prove, for example which area is causing a recurring blockage, whether a specific gully connects into foul or surface water, whether a new connection was tied in correctly, or which tenant or unit is connected to a problem line.

2) Identify access points and observation locations

We locate the most relevant inspection chambers or manholes and plan where we need to observe the network from.

3) Introduce dye into the selected drain run

We introduce dye into the drain run being tested, such as a kitchen sink, floor drain, gully, or WC line, then flush with water as required.

4) Observe and record results

We monitor chambers and key points to confirm where the dye appears, how quickly it travels, and whether flow is consistent or delayed, which can point to a restriction. Where it's useful, we can combine dye testing with other methods, such as flow testing or CCTV, to build a complete picture.

5) Findings and recommendations

You'll receive clear outcomes, typically including confirmed connectivity showing what connects where, any evidence of misconnection or unexpected tie-ins, and recommended next steps, such as CCTV, targeted cleaning, repairs, or access improvements.

Dye testing versus CCTV surveys

The two are often best used together. Dye testing proves connectivity quickly and is ideal for mapping and tracing, while CCTV surveys confirm the physical condition of the pipework and pinpoint structural defects. If you're not sure which you need, we'll advise on the most cost-effective approach based on your symptoms and site layout.

Dye testing for facilities management teams

For FM teams and property managers, dye testing can help reduce repeat reactive spend by proving the root cause, resolve tenant disputes with clear evidence, support remedial approvals with documented findings, and improve planned maintenance by giving you a clearer picture of connectivity. It's particularly useful across portfolios where drainage drawings are inconsistent between sites.

Why choose ICE Drainage?

• A commercial-first approach for hospitality and FM
• Coverage across London and the Home Counties
• Evidence-led investigations, including dye testing, flow testing, and CCTV where appropriate
• Practical recommendations you can act on
• Credentials including Safe Contractor, SSSTS, and Constructionline Gold

ICE Drainage is a specialist service expansion of ICE Cleaning, a leading sewage cleaning company in the UK.

Book dye testing

If you need to confirm drain connectivity, investigate a suspected misconnection, or trace the source of recurring drainage issues, ICE Drainage can help.

Contact ICE Drainage today, and we'll help you prove what's connected, identify the cause, and put the right fix in place.