CLEARMASTERS
in drainage
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Regulations
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The basics
What is a sampling pit for?
A sampling pit, or sampling chamber, is an access point where someone can safely take a sample of the water leaving your site, and check that it’s clean enough for where it’s going.
Sampling pits often sit downstream of interceptors and grease traps, and we can empty both. We can also remove oily or contaminated wastewater from your site.
We do this work across Surrey, West Sussex, East Sussex, Kent, Hampshire and London, with tankers and engineers in each area most days.
They’re usually needed where a discharge is regulated: the outlet of a treatment plant with an Environment Agency permit, trade effluent going into a public sewer, or the outlet of an oil or fuel interceptor.
An inspection pit is simpler: an access point for looking at, clearing and surveying a drain. Many chambers are built to do both.
How it works
How a sampling chamber works
The key is a drop between the inlet and the outlet, so a sample can be caught from falling water. Hover over or tap the numbers to see each part.
- 1InletThe flow from the treatment plant, interceptor or site drains.
- 2A dropThe inlet sits higher than the outlet, so the flow falls freely and a sample can be caught mid-stream.
- 3Sampling jug on a poleSamples are taken from the surface. Nobody needs to climb in.
- 4Channel and outletA smooth channel carries the flow on to the drainage field, watercourse or sewer.
- 5CoverBig enough for the sampling gear, easy to lift, and lockable if you need it to be.
- 6DepthKept as shallow as the levels allow, so sampling from the surface is easy.
Compared
Inspection pit or sampling pit?
| Inspection pit | Sampling pit | |
|---|---|---|
| What it’s for | Looking at, clearing and surveying a drain | Taking a sample of what’s being discharged |
| Inside | Channel and benching for smooth flow | A drop or weir, so a clean sample can be caught |
| Who uses it | You, drainage engineers and service engineers | Service engineers, the water company or the Environment Agency |
| Where | Along the drain, at bends and junctions | After the last treatment stage, before the discharge point |
| Required by | The Building Regulations | Your permit, consent or the manufacturer’s instructions |
When you need one
When do you need a sampling pit?
New treatment plants
A sampling chamber on the outlet makes it easy to check the plant is treating properly, and some permits require one.
Trade effluent consents
Businesses discharging trade effluent to a public sewer usually need a consent from the water company, which often asks for a sampling point.
Interceptors
A sampling point after an oil or fuel separator shows what’s leaving the site.
Environment Agency permits
Discharges too big for the General Binding Rules need a permit, and permits often set sampling requirements.
Upgrades and repairs
Adding one while other drainage work is going on costs far less than digging again later.
Problem sites
Where you need to prove where a pollution problem is, or isn’t, coming from.
On the day
How we install a sampling pit
Survey
We check the levels, the flows and what your permit, consent or plant manufacturer needs.
Design
The chamber is positioned after the last treatment stage, with enough fall for a drop and a cover big enough for the sampling gear.
Install
We dig, set the chamber on a base, and connect the inlet and outlet with watertight joints.
Test and hand over
We check the flow and the drop, reinstate the ground and show you where it is.
Why Clearmasters
Why choose Clearmasters?
We service treatment plants and interceptors and empty them every day, so we know what a good sampling point looks like from the engineer’s side of the cover.
Ask us a questionWe survey before we dig
Levels, ground conditions, buried services and where the water can go, checked before we quote.
Done to the rules
Designed and built to the Building Regulations, British Standards and the manufacturer’s instructions.
We look after it afterwards
We empty, jet, survey and service what we install, so you have one firm for the life of the system.
Trained engineers
Our engineers hold current confined space entry certificates, for chambers that do need to be entered.
What our customers say
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Questions answered
Sampling pit FAQs
Why are sampling pits needed for treatment plants?
They give the service engineer, the water company or the Environment Agency a safe place to take a sample of the treated water and check the plant is working. Some permits and manufacturers require one.
Does every property need a sampling pit?
No. They’re usually needed for commercial sites, trade effluent consents, permitted discharges and interceptors. For a domestic treatment plant it’s optional, but useful.
Can a sampling pit be added to an existing system?
Yes, as long as there’s enough fall between the plant and the discharge point for the drop. We’ll check the levels at the survey.
How long does installation take?
Most are done in a day or two, depending on the depth, the ground and the access.
What’s the difference between an inspection pit and a sampling pit?
An inspection pit gives access to look at and clear a drain. A sampling pit is built so a clean sample can be taken from falling water. Many chambers do both.
Got a different question? Call 03333 233566 or send us a message.
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