However, whilst the simple answer to this question is 'yes you can', there are a number of factors to consider before isolating either the whole system or areas of a larger site;
- Gaskets and seals may dry out during extended periods of isolation, causing them to shrink and crack, leading to leaks when systems are brought back online.
- Does any part of the system create dead legs in other areas? Isolating, for example one compartment of a twin compartment tank could result in dead-leg being formed in the incoming main supply. Particular attention should be paid to pipework configuration when isolating tanks and specific parts of a system.
- Are twin compartment tanks designed to have one tank drained? The design of some tanks requires that both compartments maintain equal/similar water levels/pressures to prevent the shared wall collapsing.
- Sediment and debris within the system can dry out and block strainers and valves when the system is re-instated, these sediments can also increase bacteria levels as contaminants get flushed through the system.
- The associated costs involved with the additional cleaning required of some parts of a system, following being drained down for longer periods of time.
- Lead times for the engineers and maintenance teams to attend site, to carry out the above works. Many buildings have delayed works whilst buildings are empty, potentially putting off demand, which will create bottle necks when sites prepare for re-occupation.
As with any activities such as this, always check/review your risk assessment, written scheme and/or talk to your independent consultants in advance of the work. Not only will this help avoid any unintended consequences but also allows you the opportunity to update your essential documentation with any changes and reappraise the hazard(s).