Struggling With Cold Water Systems in High End City Properties?

High end residential properties coveted by the rich, famous and business elite are sprouting up all over London. This is great news for the property market, but these buildings are not without their design challenges.

The issue that public health engineers are facing is that they have to design the cold water services (CWS) for the capacity of the building in line with the Water Supply Regulations, however these dwellings are often unoccupied for long periods, as they have either been purchased for investment or for convenience when the owner is in town. Here, Paul Gueran, Technical Sales Manager, Built Environment Services, ESG, explains how new innovations in closed water tank dosing can help public health engineers overcome this challenge.

Controlling bacteria in cold water storage tanks

Intermittent periods of unoccupancy cause an issue with the turnover of the Cold Water Storage Tanks (CWSTs) in buildings. Current regulation, Approved Code of Practice L8: The control of legionella bacteria in water systems, recommends that a tank for bulk storage of potable water should be turned over in every 24 hour period; this is to keep the water fresh, minimise the risk of stagnation and therefore the proliferation of bacteria. Town mains will generally have a small residual level of chlorine that will protect the water for a period, but chlorine will not penetrate bacteria attaching to surfaces in the form of biofilm, often referred to as ‘slime’, which can be linked to a wide range of microbial infections. Further to this, biological demand will deplete the residual chlorine rapidly.

Keeping current

Historically, a number of public health engineers have utilised Chlorine Dioxide on the incoming mains cold water supply to enhance protection in their systems, and to prevent further excessive growth of biofilm and this is one option that may have previously been considered for these high end weekday homes. However, Chlorine Dioxide levels will diminish within hours making stagnation an issue. In fact, Chlorine Dioxide on a re-circulatory loop on the CWST is not recommended because continuous re-dosing can lead to excessive formation of chlorites and chlorates in the water. L8 recommends proportional dosing to minimise the chances of over-dosing.

Good news for public health engineers

The good news is that using Chlorine Dioxide on a re-circulatory loop is not your only option…

Over the last five years ESG has been developing a perfect solution to this problem, our WRAS approved electrolytic cell… Protex! The specialist equipment has been designed to utilise the chlorides found naturally in mains water to generate chlorine (hypochlorous acid and chlorine dioxide), without the addition of any supplementary chemicals which are hazardous to transport, store and dose. ESG installs a re-circulatory loop, allowing the water from the tank to circulate continuously through the Protex! unit, boosting the levels of disinfectants to minimise bacteria seeding the system and biofilm formation on the surfaces of the tank when there is no draw off.

During the periods of low use, water stagnates throughout the extent of the pipework, which could increase risks substantially. When there is demand, the levels of chlorine (and other oxidants) generated by Protex! in the cold water tank will also disinfect the cold water services network, making it ideal for high end city apartments, where closed water system use is intermittent, and giving you and your tenants peace of mind.

In essence, Protex! can maintain your water safe from pathogens at minimal running costs with negligible maintenance. No more expensive chemicals are added to the water, removing manufacturing and transportation costs, improving your environmental impact and of course, enhancing the overall quality of your water. 

Want to find out more about electrolytic disinfection and Protex!?

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