Drop in water pressure when flushing toilet

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Scott_

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I need help... The water pressure at my daughter's townhouse measures 80 psi when nothing is open. If a sink is turned on, the pressure drops to 70 psi. If a faucet is turned on and a toilet is flushed, the pressure drops to 25 psi. She has city water (not on a well). There is a whole house filter and a water softener just after the water meter in the basement. There is no Pressure Regulator /relief value connected to the main line. The pressure issue seemed to start after I reconnected an old water softener, but not sure why the pressure would drop so badly because of this. The softener has a built in bypass and I turned it so it bypassed the softener tank but still had drop in pressure (didn't measure it with pressure gauge yet, but can see a drop in water flow). Any ideas why the pressure drops so badly?

Scott
 

Reach4

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Clogged element in the whole house filter is my first guess.

If replacing the element, you want to have an O-ring available if the system uses one. Also you would like to lubricate the O-ring very lightly with silicone plumber's grease when you screw it back together. Read up on how to change the element. Many should only be tightened hand tight during the filter change but might need a wrench to loosen the housing before removing the old cartridge.

When you pull the old filter element, take pictures. I have a feeling that such a picture would be interesting.

Now there could be a different cause of the pressure drop. Those would have much more involved cures.
 

Jadnashua

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Some filter assemblies have a bypass position...try using that if you have one. As was said, that is the more likely source of restriction. But, it could also be the softener, or a valve that is not fully opened, or if there's any galvanized piping in the house, that often rusts from the inside out, and could have the effective ID of a pencil. With no flow, pressure is fine, but any flow (and a toilet's supply line is fairly small), that restriction becomes the biggest problem.
 

Scott_

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Reach4 and Jadnashua... Thank you for your help. I set both the whole house filter and water softener to their bypass positions and the pressure drop went away. I replaced the water filter, turned the filter and softener back to their open positions and the water pressure is much better. It still drops when there are multiple water sources open but it's not noticeable.

Reach4, I didn't take any pictures because the filter I took out looks like new. In fact I didn't suspect it was the filter originally because it sits in a clear housing and when I looked at it through the housing it looked so good I thought there must have been a different issue causing the drop.

The system set up is; village water supply ---> water meter ---> water softener ---> whole house filter ---> to house. I'm wondering if the filter is getting clogged up with salts from the water softener (not visible to naked eye). I haven't seen anything online saying putting the softener before the filter is wrong, and I thought it would be better to remove any salt from the drinking water, but now I'm wondering if I need to switch the order.

Does anyone know if there is a correct order to hooking up a water softener and whole house filter?
 

Reach4

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I can't see salt clogging your filter unless it was an RO membrane, which I am confident it is not. What is the brand and model of the filter element that you are using?

I would put a whole house filter in front of the softener, but I don't see a problem with putting one after.
 

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Hi Reach4... You're correct, it's not a reverse osmosis system. The filter housing is a GE Whole House unit (model # GXWH40L) and the filter is GE model FXHTC, which is a carbon spun fiber filter rated to remove sediment and chlorine taste . It's rated as a high flow unit.
 

Reach4

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https://www.geapplianceparts.com/store/parts/spec/FXHTC

I don't see an obvious mismatch to the job. 25 micron is a moderately loose sediment filter, but it appears to be primarily a granulated activated carbon (GAC) filter. If it were a carbon block filter, that would be different. If the water was not chlorinated, I would worry that something is growing in the element. In the specs I see the
Max. Filtered Water Flow (gpm) 15.0
Rated Filtered Water Flow (gpm) 4.0​
I presume the difference in the two flows is how much pressure drop there is.

10*4.5 is a standard size, so you could probably get alternative cartridges. They suggest replacing the O-ring. I suggest lightly lubing the O-ring with silicone grease each time you change the cartridge, and keep a spare on hand. My filter cartridges are 4.5*20. I got those before I decided to put the iron+sulfur filter at the front end, so my cartridges have very little to do . I think I am at about 17 months on the cartridges right now. I have the replacements standing by.
 

Jadnashua

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If I'm interpreting those numbers correctly, to obtain the desired filtering of chlorine and other tastes, you should not draw more than 4gpm...but, it is capable of passing as much as 15gpm. It takes some exposure time for the activated charcoal to absorb contaminants from the passing water. It doesn't take much particulate contamination to start to clog a typical filter, so bigger is better. But, a normal water supplier is held to some standards about particulates...and, for the most part, it's not a big deal and the water should be fairly clear.
 
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