I am preparing to get an under-sink RO system with pressurized storage tank for
both drinking and aquarium use, and have a question about the auto shut-off
(ASO) valves included in most systems.
When the ASO valve is activated it shuts down the input to the RO cartridge and
causes the pressure differential across the membrane to decrease (and maybe even
reverse). If residual water remains in the cartridge, will this situation allow
any significant amout of impurities to pass from the "dirty" side to the "clean"
side of the membrane, especially at night when this condition would last for
Would it be better to shut off the flow at the brine (dirty) output of the RO
cartridge rather than the input? If so, are there any valves that would do this
based on the pressure in the storage tank, just like the regular ASO does?
Or am I making a mountain out of a molehill?
Thanks for any info.
You can get the following -
Or from AquaticReefSystem
You do not really need a resoviour / pressurized tank to have a drinking
water. You just simply get slow output. The pressure tank will give you
quicker product water + product water directly from your RO.
If you want a pressurized tank and already have a RO [RO/DI], you can get it
from above link or from anywhere else like HomeDepot. You just attach that
tank to your RO product output water line with a "T" valve. The "T" valve
will let you be able to turn off/on the flow when you need it.
If you are overly concerned with TDS creep in your membrane, don't use the first
minutes worth of water. However, if that water is going to be pumped into a
it would take a lot longer than a few minutes to purge it all out.
I guess I wouldn't worry about it. Compared to the water coming out of the tap,
are way ahead of the game.
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The issue you bring up is something that can happen after the shutoff
activates. You will get a SLIGHT blend of the water from the "dirty" side
of the R/O membrane. This blend may be very insignificant. One thing we
recommend that our customers do to guarantee the highest quality water
possible is to completely drain their resevoir tank once/month. This will
remove any lower quality water and replace it with brand new water.
When we test our customer's R/O systems, we drain their tanks before we test
it. This is to ensure that we are testing the water straight from the
module, instead of a possible blend water sitting in the tank.
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