Dye testing

Introducing a coloured dye at one point and watching where it appears.

What this page cannot establish

Dye testing cannot establish the condition of any pipe
Dye testing cannot establish the absence of a connection, from a negative result alone
Dye testing cannot establish the route between the two points

What it is for

To establish whether two points are connected, by observing whether dye introduced at one reaches the other.

When a professional may raise it

These are circumstances, not rules. No method is appropriate everywhere, and a professional declining to use one is not necessarily cutting a corner.

when it is unclear which drain connects to which line
when a connection is suspected but not documented
when an operating authority asks for it as part of a process

What to ask for afterwards

A method performed without a record produces very little you can carry into the next conversation.

a written note of where dye was introduced and where it was observed
the observation period

Practical constraints

requires access to both points
a negative result within an observation period is not proof of no connection

Questions worth asking

Where was the dye introduced, and where were you watching?
How long did you observe?
What would a negative result mean here?

What would change the answer

a written note of where dye was introduced and where it was observed
the observation period

What to do next

A test result is only useful later if what was introduced where, and what was watched, was written down.

Record what was tested and what was observed

If your situation is different

You are trying to establish a shared line: Shared laterals

Shared laterals
Connection questions are usually shared-line questions.