The fresh water system is often less about comfort than about health and self-sufficiency on passage. The survey follows the line from tank to tap, the water heater and any watermaker.
From tank to tap
- Tanks
- Material, mounting, venting and access. On stainless tanks, look for weeping around weld seams.
- Pump and accumulator
- A pump that cycles on and off often points to a leak or a flat accumulator.
- Water heater
- Heated by the engine and an electric element. The relief valve is tried; connections are checked for leaks and corrosion.
- Hose and fittings
- Drinking-water-grade hose, clamps, and joints behind linings.
Watermaker
A watermaker turns seawater into drinking water by reverse osmosis. On the survey it is run and checked for:
- Output: litres per hour, against the rated figure.
- Salinity: the salinity meter reading of the product water; a rising value can mean a tired membrane.
- Pre-filters and high-pressure pump: condition and leaks.
- Lay-up care: whether the membrane was preserved when unused; ask for records.
Continue with this topic
- Plumbing and pump renewal: Bilge, sanitation and fresh water.
Water quality
The quality of fresh water aboard depends on tank cleanliness, hose type and how long the water has stood. Water left standing changes in taste and smell; sediment and a biological layer can form in the tank. Cleaning the tank regularly, using drinking-water-grade hose and flushing the system at the start of the season keep the water good. A separate filter or a separate drinking-water source is a common choice for drinking.
Points to watch on the water heater
The heater has a heat exchanger fed by the engine's cooling circuit and an electric element. A leak at the engine circuit connection can let coolant into the heater or fresh water into the engine circuit. A working relief valve, secure mounting and running the element only when the tank is full are points watched on survey and in use.
Using the watermaker properly
A watermaker should run in clean, open seawater. Running it in a marina, harbour or murky water clogs the pre-filters fast and can damage the membrane. When not in use, it is cleaned and preserved to the maker's instructions. Measuring the product water's salinity regularly is the easiest way to follow the membrane's condition.
At lay-up
At lay-up the fresh water system is drained or protected against frost; the watermaker is left with preserving solution per the maker's instructions. At the start of the season the system is refilled and flushed and every connection checked for leaks.
Planning capacity
Tank capacity, daily consumption and the watermaker's output together decide how long the boat can stay independent. On long passages, water use aboard is planned the same way as fuel.
What the pump's sound tells you
If the fresh water pump cuts in by itself with the taps closed, there is a leak in the line or the accumulator has lost its air. A pump running on without stopping can mean the tank is empty or the line is drawing air. Listening to it is the easiest way to catch a problem early. When looking for a leak, the water heater, tap connections and hoses behind linings are checked first.
A small leak behind a lining can rot joinery over months.