I have the counter top water filtration system. It is leaking from the back underneath. Can I fix this?

give them a call
http://www.ghpgroupinc.com/CTUS.html

MAKE SURE THAT WHEN YOU REPLACE THE FILTER IT IS IN THE SAME ORDER AS THE ONE YOU REMOVED OR THAT IT IS THE SAME MODEL TYPE REPLACEMENT , I WOULD TRY TO TURN IT AROUND FIRST , A THIN WRAP OF "WHITE PLUMBERS TAPE" , AROUND THE SCREW TOP INNER SEAL MAY CORRECT THE LEAK , ABOUT THE FILTER , WELL , IT MAY JUST BE SIMPLY IN THE REVERSE ORDER , TRY TO FILP THAT OVER , AND WHEN YOU RESEAL THE CAP ON THE FILTER MAKE SURE THAT THE SEAL IS ON PROPERLY , APPLY PLUMBERS TAPE ONCE AROUND , AND *"BEFORE YOU TIGHTEN IT" , GENTLY , REVERSE THE CAP BACKWARDS , SLOWLY , UNTIL YOU FEEL IT "SEAT " PROPERLY , "THEN" YOU MAY TRY TO RE-TIGHTEN IT . THIS SHOULD REMEDY YOUR LEAK , IF IT CONTINUES MAKE SURE THEN THAT YOU HAVE THE CORRECT REPLACEMENT FILTER MODEL FOR YOUR PARTICULAR ITEM . HOPE THIS HELPS YOU . NOW GO FIX IT ! GOOD LUCK .

Make sure any water valves (Cold or Hot) for water heater are not leaking first. Gate valves may leak at the packing nut over time and drip on top of tank. If water is leaking from the top of the water heater itself the tank is corroded and water heater will need to be replaced.
RJ

If it's leaking from a hose then you can try unscrewing the hoses, put some Teflon tape on the water heater threads and tighten. If it's leaking from the rim or under the threads call a appliance repairman.

You need to cut water supply to filter, you may want to put a bucket or something to catch water under it, then, press the button on filter to release pressure in filter. If you have a wrench for it, the wrench should slide up from bottom and engage ribs on side of filter. Turn counter clockwise to remove, sometimes you can do this by hand. You can also use a strap wrech, just don't break canister. You also want to try not to strain your pipes if they are not supported. Any way, you may have to figure a way to grip canister to twist off. You do not want to overtighten for this reason. After you change your element, make sure the o-ring in the lip inside of canister is in place. Twist back on, clockwise. Turn your water on and check for leaks.

That is the drain for the reverse osmosis system. You have what is referred to as an AIR GAP faucet. The waste water is pushed up there before it goes to drain just as the drain for a dishwasher does. If water is coming out of the faucet the drain is most likely plugged or the line is kinked causing water to back up and overflow. Check the drain line for kinks and clean out the drain where it attaches to the stand pipe.
RJ

did you check your pressure relief valve,usually on the top of the heater,it has a spring activiated handle on it

If it is coming from the canister, pull it off, check the o-ring, it is probably pinched. It will need to be replaced.
RJ

The red button is a pressure relieve valve. If the system is leaking from the valve, try pushing the valve up from the underside of the cap where the valve is located. If this does not work the housing needs to be replaced. You do not have to replace this with a name brand like GE. All you need to do is make sure the housing that you are purchasing is the same size.

Example of Replacement Filter Housing: http://www.freshwatersystems.com/c-107-filter-housings.aspx

FreshWaterSystems.com: The Water Super Store: 1-877-335-3339

before putting cover on, chk the button to make sure it isn't staying depressed and see what the button is doing when depressed. The cover may have to be in a certain position. with the cover in place, gently rotate untill button pops up