A yacht’s water tanks can be a lively breeding ground for undesirable bugs, especially in warm climates, however, a sub-micron filter will render the water safe to drink.

Fresh water systems rarely get a great deal of attention, and yet all crews depend on them for their very survival. However, winterising the system at the end of the season is an ideal time to assess whether any upgrades would improve the system.
The most important element of this is to protect the system from frost damage. It’s important not to be complacent about this, even with boats that are based in the Mediterranean – those who have wintered in many areas can attest to the possibility of sub-zero temperatures on the coast of almost anywhere on the Med’s European shores.
The first task is therefore to empty as much water as possible from the system, including the water heater. If possible do this via a drain valve into the bilge and then use the vessel’s main bilge pump to clear the fluid – this will save wear and tear on the freshwater system pumps as well as giving a check of the bilge pumping arrangements.

Failure to properly winterise the system can lead to costly – and inconvenient – damage.
In many cases it’s not possible to be certain that all the pipework is drained of water, but non-toxic antifreeze, designed for use with yachts and motorhomes, can be pumped around the system. It’s then removed, and the system flushed with clean water when re-commissioning in the spring. Before adding the antifreeze make sure any filters have been by-passed and make a note to replace them in the spring.
Common upgrades include installing a manual pump for use in the event of failure of the main electric pump. In some cases this can also help to reduce water consumption. While many yachts have simple carbon filters that improve the taste of tanked water, few have the ultra-fine 0.4 micron filter that’s needed to ensure bacteria and viruses are eliminated from the drinking water supply.

These are easy to fit, don’t require additional water pressure, and eliminate any need to carry bottled drinking water. Installation costs are typically a few hundred pounds, and annual maintenance – primarily replacement of the filter element – around £100.