Aptus provides a full water supply and connection service which includes hydrostatic testing and disinfection of mains and water sampling. Our expert engineers travel all over the country in their high-spec, custom-built vehicles, testing new-build properties to ensure the water supply on our clients’ developments is safe and ready for residents moving in.
Every day is different, and each job requires a fresh approach.
My day starts with opening my job pack to confirm where my job will be for the morning, who the developer or client is and the water provider for that area. The pack also includes details about the size of the water main, as-laid drawings, and the location of the back-to-back hydrants where the test is to be carried out. I use this to establish a method to prepare the main for testing and chlorinating.
I cover the North West so my job can take me as far south as the Midlands and right up to Cumbria so I may have a bit of travelling to do before arriving at the location. When I arrive, I make myself known to the site manager, sign in and may have an induction to go over any health and safety procedures. Sites can vary in size and there can be more than one developer and multiple contractors working at once, so inductions are necessary to keep everyone safe.
When I arrive at the section for testing, I park the vehicle in a suitable safe position with a constant view of the back-to-back hydrants. It’s important to assess the work area and fill out a risk assessment, I also double-check the drawing and my method and prepare the main ready for testing.
Each job varies and I may be testing a 10 metre main which will be connected to an apartment block, or a half-kilometre main serving an entire development. However, the process for testing remains the same and involves preparing the main for testing and ensuring it is clear of any pockets of air, followed by pressurisation of the main, chlorination and sampling.
Every development is different, and residents may already be occupying some of the properties, so the next step is to secure the area by erecting safety barriers to ensure any pedestrians or workers moving about the site are safe.
I head to the first point where water will be discharged and place the standpipe on the hydrant. This may need digging out if there has been a build-up of soil and debris. I expose any necessary hazards and apparatus and update the risk assessment. I next prepare the main for testing by slowly opening the live hydrant that is feeding my section, to remove any debris. I use plenty of chlorine spray to ensure all the equipment is properly disinfected and the live hydrant is sterile.
When the water runs clear a swab is sent through to clear the main of any pockets of air. This is followed by opening all relevant valves and hydrants to make sure they expel clear water – a sign the air pockets have been removed – then ensure all the ends are closed ready for testing.
The final step before pressurising the main is to replace the frost plug, which is an important piece of equipment that protects the hydrant in cold weather. It is also the source of potential leaks. I then make sure the housing it sits in within the hydrant spout is properly chlorinated and the whole section is secure.
Once the main is ready for testing, I call Ant Hire, who are our pressure testing partners, and give them details of the diameter and length of the main and pump size. They inform me how long it will take to pressurise the main if at the starting point it contains zero air. The maximum amount of air permitted in the main before it qualifies as an immediate fail is 8%. Therefore, if the pump runs longer than the time stated by Ant Hire, I apply the swab to the main and try again.
The test lasts 60 minutes. Ant Hire will call to confirm whether the test has passed or failed. If it fails, we work together to solve the problem, and I can proceed to chlorinating the water main.
Chlorination is the final phase and for this I use a Dosatron dosing pump to feed the tested section with chlorine at 25 parts per million (ppm). The presence of chlorine is first detected by smell, then confirmed by using the industry standard DPD3 chlorine tablet which shows it has reached the required strength. Once all ends are chlorinated, I proceed to the section and release pressure from the chlorinated main.
The mains must have a minimum amount of 16 hours contact time with the chlorine, so I return the next day to take a sample. Once again, a swab is used to help remove the chlorine and give the main one last clean before taking a final sample. A DPD1 tablet is used to show when the chlorine has been removed and ensure the main is safe to carry water fit for human consumption. Once samples are taken from all ends of the tested section they are transferred to a laboratory for analysis.
At this stage the test is now complete and the main is ready to be connected to the existing network. I remove all my equipment and ensure the work area is safe and tidy before I sign out, and then it’s onto my next job.