Water Usage

For 216 days of our voyage, we lived on the fresh water we could produce ourselves. A small handful of times we filled up from reusable water jugs, but the vast majority of our water came from the reverse osmosis water maker we have on Eventide. This device takes sea water and creates fresh water by pumping the sea water at a very high pressure through very fine filters. Pure H2O gets “squeezed out" and the remaining salt and other compounds are pumped overboard.

To understand our usage, we kept detailed logs of when we used the water maker and how much water we produced each time. We measured water levels using an analog gauge that is attached to float sensor in the water tank.

We can learn a couple of things by looking at this data. First, how efficient is our water maker - it is rated to produce 100 liters an hour, did it? Second, how much variation is there in production? Third, how much fresh water did we consumer per day?

• First, on average, our 100 liter per hour Dessalator produced 70.5 liters per hour.

• Second, there isn't a strong correlation between hours run and liters produced. Age of pre-filter also doesn’t make a material difference. Salinity and temperature of the sea water are likely the big factors, but we did not measure these each time.

• Third, how much fresh water did we consume? We use fresh water to wash dishes and hands, shower, rinse off after swimming, and flush on-board toilets. During this 216 day period, we produced 13,000 liters from the water maker. We likely got about 2,000 liters from jugs over the same period. This equates to 70 liters per day of consumption, or 18.5 gallons per day, for the 5 of us.

Now for some charts.

A scatter plot picture of water produced per hour and hours run for each of our runs. Orange dot is the average run - just under 2.5 hours and just over 70 liters per hour produced.

Cumulative water maker production