The chlorination certificate records that a water system has been cleaned and disinfected to BS 8558 and BS EN 806. It covers two jobs that use the same procedure: the annual clean and disinfection of a cold water storage tank, and chlorinating new pipework before it goes into service.
It sits on the Gas tab in New certificate, alongside the legionella risk assessment and the unvented hot water record, because that is where the plumber doing the work looks.
It is not a gas document
You will not be asked for a Gas Safe number and none prints. Disinfecting a water system is not a Gas Safe activity, and the certificate's declaration says what the trade's own paperwork says: that the work was carried out by competent persons, to BS 8558 and BS EN 806.
Say what you disinfected first
That one choice changes the rest of the form:
- Pipework asks for the material, diameter and length, and does not ask you to set a next date. Chlorinating a new main happens once.
- Storage tank or Whole system asks for the tank's location, material and capacity, and adds two boxes the law wants on a tank record: what condition you found it in, and what you have recommended or already put right. It also suggests a next clean twelve months out, which puts the tank into your renewal list.
That second point matters. Under a written control scheme a stored tank is cleaned and disinfected together, once a year. Cleaning it without disinfecting does not satisfy the scheme, and a record that does not say what you found does not meet it either.
Working through it
The form follows the job in order, so you can fill it in as you go:
- Before disinfection. Whether you flushed first, and the chlorine residual you measured afterwards. Every residual is asked as a pair, free and total, because that is how you read them.
- Disinfection. What solution you used, the residual after dosing, how long you left it, and the residual at the end of the contact time.
- Flushing back. Whether you got it back down to the background mains residual, what it read, and how long you let it stand before sampling.
- Tests and sample. The residual after standing, appearance, taste and odour, and whether you took a sample for coliform and E. coli.
Mucka will not tell you a residual is wrong or a contact time is short. You record what you measured and you make the call. That is the rule across every certificate here: none of them turns a standard's figure into an automatic pass or fail.
The lab result can come later
If you sent a sample off, the result usually takes two to five days. You do not have to wait to approve the certificate. Leave the lab result as "Not recorded yet" and approve, and the certificate prints Awaiting lab where the result goes, which is the honest thing for it to say on the day.
When the lab comes back, open the certificate and use Correct this certificate. That gives you a fresh draft with everything carried over, you set the result to Satisfactory or Not satisfactory, and approve it. The original stays on file marked superseded, so there is a clean trail of both.
There is no pass or fail on this certificate. You would not issue one for a disinfection that did not finish, so the thing the customer actually wants to see is the sample result, and that is what prints in the top corner.
What comes out
One landscape page: who did it and where, what was disinfected, the readings at every stage, the sample, what you found and what you recommended, and the declaration with both signatures. Approve it and Mucka allocates the serial, renders the PDF and offers to email it.