We've been using a Spectra 16 GPH system with two feed pumps since 1999. The system has a wire mesh strainer to get the big stuff out and then a 20 micron and 5 micron prefilter.
My wife has been involved in public water supply and quality management for the last 30 some years and is very particular about her drinking water
Our objective measure is less than 500 ppm measured with a calibrated HANNA TDS1 meter. Our subjective measure is no odd smell or taste.
Our typical ppm readings are 180 - 250 but have drunk water with a TDS reading of 550 ppm with no problems. Frequently we have to run the pressurized watermaker
for 10 minutes or so to get rid of the odors before we allow the product water to be piped into the water tank. We have a cockpit
valve that allows the product water to be piped over the side with a discharge port that we can reach from the cockpit
. We just put a clean glass under the port, gather a sample, sniff test it, test for TDS, and then taste test. Once it passes all those tests we change the valving to allow water into the tank.
Our most common subjective quality complaint is a faint "grassy" odor
to the water when the prefilters need to be changed. This can occur in as few as five hours run time in water with lot's of plankton growth or as infrequently as 30 or 40 hours in pristine clean water.
Our worst quality problems have been in Puget Sound
in 50 degree water when there was intense plankton bloom. The wire mesh screen
would clog in just a few hours run time and the 20 micron filter needed replacement every four or five hours run time.
The ppm TDS increases significantly when we run with only one feed pump. Using two feed pumps generates 120 psi feed water to the Clark Pump but running only one feed pump generates only 95 or so psi and results in TDS of 325 - 450 ppm instead of the normal 180 to 225 ppm.
Other folks I know with watermakers accept tds ppm of up to 600 with no problems.
Our Spectra with two pumps running makes 15 - 16 GPH while using 17 amps of 14.4 current
. We have 600 watts of solar panels
so have no problem making that kind of power.
While cruising we run the Spectra at least one hour per day, every day to keep it fresh. That means we always have too much water and take frequent showers and wash the decks with fresh water every couple days.
The more you run a Spectra the better it performs so we run it in non-pressurized mode (water is not being forced thru the membrane) for several hours a day if we are running the diesel
We are still using the original membrane that came with the Spectra when I installed it in August 1999. Other Spectra users I know have gotten even more life out of their membrane.
I've replaced the following components int he 13 years we've had the Spectra:
over pressure switches
Pre-Filter Cannister housings
Clark Pump main body
The Spectra was a great system 13 years ago and is even better now.