Changing Filters When replacing the primary filter of any RO appliance equipped with a permeate pump, be sure to follow the
purge procedures exactly. Failure to do this may result in premature failure of the permeate pump due to an “air
locked” condition created when entrained air enters the brine cavity of the permeate pump. This condition stalls
the valves of the pump and will either stop brine flow or allow continuous flow to the drain.
Note: Whenever any filter is changed, sanitize the appliance. See Sanitizing the WaterMax RO Appliance.
Caution: Lubricate O-Rings with glycerin. Never use a petroleum-based lubricant where it can contact the
O-Rings.
Changing the Sediment Pre-Filter
1. Turn off the ball valve on top of the storage tank 1/4 turn
clockwise. (See Figure 2).
2. Turn off the feed (cold) water supply valve. (See Figure 12).
3. Lift the black handle on the dispensing spigot and wait at
least five minutes for the pressure to be relieved from the
appliance.
4. Remove the Pre-Filter housing by turning it counterclockwise
(as viewed from the bottom). If you encounter difficulty, use
the filter wrench provided with your RO.
5. Inspect the Pre-Filter. If it is visibly dirty, discard it.
6. Wash out the filter housing using warm, soapy water and
rinse thoroughly.
7. Sanitize the appliance. See Sanitizing the WaterMax RO
Appliance.
8. Be sure the O-Ring is properly seated in the groove that is
located in the top of the filter housing and lubricated with
glycerin.
9. Insert the new Pre-Filter. (For correct operation, the correct
pre-filter designed for your particular model MUST be used).
(See Figure 16).
10. Reattach the filter housing.
11. Purge the air out of the filter by removing the 1/4-inch locking Figure 12: Feed Water Supply Valve
clip from the elbow connection from the fitting in the “out” port
on the Pre-Filter cap. (See Figure 17, Item 1).
12. Connect a suitable length of 1/4-inch tubing to the out port and route to the sink. Turn on the water
supply and flush the filter until the water runs clear and steady.
13. Turn off the feed water supply and remove the flush tubing.
14. Reattach the red feed tube and the 1/4-inch locking clip to the fitting on the outlet fitting.
15. Turn on the feed water supply valve and check that the permeate pump is functioning properly. Let the
water run for ten to fifteen minutes to confirm consistent performance.
16. Close the tank valve to check for proper shutoff valve function. When the permeate pump stops cycling,
the water flow has shut off.
WaterMax RO Owner’s Manual 11/11/2009 24