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Graf Treatment Plant Servicing

Servicing and repairs for Graf Klaro and One2Clean treatment plants, across Surrey, Sussex, Kent, Hampshire and London.

Servicing and
repair engineers
24/7
call-outs
Clear report
after every visit
Our own vans
and tankers
34 years
in drainage

The basics

What makes a Graf plant different?

Graf Klaro and One2Clean plants are sequencing batch reactors, or SBRs. Instead of treating wastewater as it flows through, they treat it in batches, in a timed cycle run by a control unit.

Your plant will also need regular desludging, and we can do both on the same visit. We service the other main makes too, including Marsh and Rewatec (Conder).

We do this work across Surrey, West Sussex, East Sussex, Kent, Hampshire and London, with tankers and engineers in each area most days.

There are no electrical parts in the tank. The compressor and control unit sit in a cabinet outside, and the water is moved around by air-lift pumps, which makes them reliable, but it means the cabinet, compressor and valves are the heart of every service.

How it works

How a Graf SBR plant works

Watch a Graf Klaro go through its cycle. A One2Clean works the same way, but in a single tank.

How a Graf Klaro SBR treatment plant works Animated cycle of a sequencing batch reactor. Wastewater collects in the primary chamber. In turn, a batch is lifted into the reactor, air is bubbled through it to treat it, the air stops so the sludge settles, and the clear water at the top is lifted out to the outlet. Then the cycle starts again. FILL 12345

  1. 1Primary chamberWastewater collects here and the solids settle out.
  2. 2Feed lifterAn air-lift pump moves a batch of wastewater into the reactor.
  3. 3SBR reactorWhere the batch is aerated, settled and emptied of clear water, in a timed cycle.
  4. 4Control unit, compressor and diffuserHoused in a cabinet out of the tank. It runs the cycle and supplies the air.
  5. 5Clear water lifterLifts the clean water off the top of the reactor to the outlet.

What we service

What a Graf service involves

We follow Graf’s own service guidance, including:

Compressor

Cleaning or replacing the air filter and checking the compressor is delivering enough air.

Valves and air-lifts

Checking the solenoid valves and each air-lift pump, so water moves between the stages as it should.

Diffuser

Checking the aeration pattern in the reactor and clearing a blocked diffuser.

Sludge test

Graf use a settling test to decide when to desludge. We carry it out and tell you if it’s due.

Control unit

Checking the cycle settings, fault log and alarms, and that the cabinet is dry and ventilated.

Log book and report

We record the service, so you have a history for your plant.

Between services

Keeping your Graf plant healthy

Do

  • Keep the compressor cabinet vents clear
  • Listen out for changes in the compressor’s sound
  • Use cleaning products sparingly
  • Keep lids and covers secure
  • Call us if the control unit shows a fault

Don't

  • Let rainwater or surface water into the plant
  • Switch the plant off, even when you’re away
  • Flush wipes, sanitary products or fat
  • Tip bleach or chemicals down the drains in quantity
  • Open the cabinet or tank unless you’re trained

On the day

What happens on a Graf service

  1. We check the cabinet

    Compressor, filter, valves and control unit, including the fault log.

  2. We check the tank

    The aeration, the air-lifts and the condition of the tank and pipework.

  3. We test the sludge

    A settling test tells us whether the reactor needs desludging.

  4. We record and report

    We fill in your log and explain what we found.

Book a service Call 03333 233566

Why Clearmasters

Why choose us for your Graf plant?

SBR plants reward regular care. We know how Graf plants work and what they need, and we can desludge them too.

Ask us a question

Always on hand

Planned servicing at a time that suits you, and 24/7 call-outs when something goes wrong.

Straight answers

We explain what we found in plain English, and give you honest advice on what needs doing now and what can wait.

Trained engineers

Our engineers hold current confined space entry certificates and work on treatment plants, pump stations and drainage every day.

Desludging done properly

Graf plants should be desludged leaving some water behind. Our crews know how.

What our customers say

9.84/10

Checkatrade

From 134 reviews · Read them
4.9/5

Google

From 63 reviews · Read them

Scores as of September 2026

Read all our reviews

Questions answered

Graf servicing FAQs

How often should a Graf plant be serviced?

Graf recommend servicing a One2Clean at least twice a year, roughly every six months. Klaro plants should be serviced one to three times a year, depending on the size and load.

What’s the difference between a Klaro and a One2Clean?

A Klaro has a primary chamber where solids settle, and an SBR reactor where the batch is treated. A One2Clean is a single-tank SBR, where wastewater goes straight into the biological zone.

How do I know when my Graf plant needs desludging?

Graf use a settling test, which shows how much sludge is in the reactor. When it passes the manufacturer’s limit, it’s time to desludge. We do the test on every service.

The compressor is louder or quieter than usual. Is that a problem?

It can be. A change in sound often means a worn diaphragm or blocked filter. Give us a call and we’ll take a look before it fails.

Is desludging part of a service?

No, desludging is done by one of our tankers and charged separately, but we can arrange it for the same visit. Your engineer will measure the sludge and tell you when it’s due.

Is servicing a legal requirement?

The Environment Agency’s rules say your plant must be operated in line with the manufacturer’s specification, and should be regularly maintained in line with their instructions by someone competent. If your discharge causes pollution, the first question you’ll be asked is when it was last serviced. A regular service is the simplest way to stay on the right side of the rules.

Got a different question? Call 03333 233566 or send us a message. You can also read the rules on GOV.UK.

Related services

Treatment Plant ServicingServicing for every make of treatment plant. Treatment Plant DesludgingSludge removal, arranged alongside your service. Control PanelsRepairs and replacements for plant and pump controls. Drainage FieldsNew and replacement drainage fields.

Fully accredited & compliant

We're independently vetted and certified so you can trust who you're letting onto your site.

SafeContractor

Health & safety pre-qualification accreditation, verifying our processes meet recognised safety standards.

RISQS

Railway Industry Supplier Qualification Scheme — approved to work safely within the rail industry supply chain.

Achilles UVDB

Utilities Vetting Database membership, confirming we meet the utilities sector's supply chain standards.

Trading Standards Approved

Vetted and approved under the local authority's trusted trader scheme for honesty and fair dealing.

NADC Member

Members of the National Association of Drainage Contractors, the UK trade body for the drainage industry.

Registered Waste Carrier

Registered with the Environment Agency, so your waste is handled and disposed of fully within the law.

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