A number of factors need to be taken into consideration when choosing a desalinator:

1. The number of people on board?

2. How much water they are likely to use in a day?

3. Will you be using dishwashers, washing machines or showers?

4. Running time of generator/engine.

5. Type of drive – Engine (DC) or Generator (AC).

6. Space availability.

How much water can a person use in a day?

Typically, each person will use at least 10 litres of water and the average is 50 litres per day. On commercial vessels the industry standard average is calculated at 160 litres per day, plus an allowance for any other equipment such as refrigeration or processing.

If you have a washing machine or dish washer, these count as extra people.

It will also be worth considering how frequently showers are used if you have them on board.

When you have taken all of these factors into account, the following formula can be used to calculate your total requirement:-

Number of person x Litre/person = Litre/Hour
Running Time (Hours)

Engine/generator running time

This may be as little as two hours in twenty four, limited to battery charging, food preservation and desalinating, so you would need to produce a day’s supply of water in two hours. If, of course, you run longer generator hours for air conditioning then a smaller output desalinator will produce a day’s supply over a longer period of time.