The Kenmore unit I have only has a carbon pre filter, membrane, then post filter. All the ones I've looked at at lowes or hd do not have any uv or anything special. How are millions of people not getting sick?
If you recall, I pointed out the chances of a problem were not that high, but obviously it is a potential concern since most manufacturers provide a UV option.
So let's take a look at a unit from Home Depot that doesn't use a UV.
It has lots of warnings about bacterial contamination and recommends an extensive internal bleaching procedure to reduce bacteria with each filter change. If you are following that, then the chances of a problem are minimized. Are you bleaching the inside of your unit every time you change a filter? Probably not, unfortunately, if you drink it.
http://products.geappliances.com/Ma...ispatcher?RequestType=PDF&Name=49-50198-1.pdf
from it:
Sanitizing the Reverse Osmosis System
Sanitize upon installation of the Reverse Osmosis
system and after servicing inner parts, including
replacement of prefilter, postfilter and the
membrane cartridge.
Be sure to wash your hands before handling
inner parts of the system.
CAUTION: Before sanitizing, be sure to
remove all cartridges. Chlorine will destroy the
Reverse Osmosis membrane cartridge.
1. Follow steps 1 through 4 under Prefilter,
Postfilter and Reverse Osmosis Membrane Cartridge
Replacement Procedure.
2. Fill the empty canister labeled "œSanitization
Canister" with water to within 1 inch of the
upper opening. Add 1 oz. (2 Tbsp.) ordinary
household bleach. Install canister into the
prefilter canister position by turning to the right
about 1/3 turn until the alignment marks line
up and the canister stops.
3. Install the two additional "œsanitiziation canisters"
into the membrane canister and postfilter
openings in the manifold by turning to the right
about 1/3 turn until the alignment marks line
up and the canister stops.
4. Turn ON water supply. Turn ON faucet until
water begins to flow from the faucet, then turn
faucet OFF. Allow system to fill for 10 minutes.
5. Turn faucet ON and allow water to flow for 20
minutes, or until bleach odor is gone. Turn OFF
water supply again. Turn ON faucet to drain
the system.
6. Once the system is drained, turn the faucet OFF
and remove the canisters by turning to the left
about 1/3 turn. Keep these in a safe place until
needed the next time.