cold water running slow

[cleanclear1]

this morning i was messing with the backflow preventer (long story) shut off one of the switch then turn it back on. then all of my machines doesnt have cold water. found out that the strainer on the hose is full with tinny rocks or sediment, had to clean each machine. now when cold water is selected on my washer, water comes out slowly, very weak, seems like something is stuck inside the valve. when hot or warm is selected the water runs normal strong and fast, but when it gets to the rinse cycle, it becomes slow again. all my rinse cycle runs on cold water. i put the hot water hose into the cold water valve on the machine just to make sure all the valve and hose are clean, it runs fine.
before all this happen my cold water cycle always runs slower than hot water cycle.
any idea? maybe something to do with the backflow preventer?

[Howard]

Most definitely NOT the backflow preventer. If it was then your hot would be slow also as ALL the water first enters the flow preventer. Something has gotten into your cold water supply and the line needs to be flushed. It may have also gotten into the hot but dropped out in your hot water heater or tank - they should probably be flushed too.

[canon]

Check cold hoses again. You may have two strainers. One on the hose gasket and one in the valve it self. You will have to spray in water valve and clean with a small brush.

[petefritz]

If you are saying ALL your washers are affected by you messing with the backflow then something is wrong with it, maybe a valve stuck or something. Call the city water dept and complain, don't say you messed with it!
Another reason why not to touch perfectly good working plumbing..

[Howard]

Originally Posted by petefritz

If you are saying ALL your washers are affected by you messing with the backflow then something is wrong with it, maybe a valve stuck or something. Call the city water dept and complain, don't say you messed with it!
Another reason why not to touch perfectly good working plumbing..

NO!

The OP said that it is only impacting cold not hot, thus it is not now the backflow preventer. There may have been something there that got into the lines, but the problem is not there otherwise the hot would be restricted just the same. I would bet a bunch of crap is in the lines, and in the bottom of the water heater where it dropped out and did not impact that screens in the washers - yet.

[cleanclear1]

i only known one strainer on the 3 way valve where it connects to the water hose, where is the other one?

been two days now, clean my strainers twice on all the machines and also change diaphram on few machines. i think is safe to say all the sediments are gone. notice one thing today, when there are multiple machines running water is slow, but when there are fewer machines it runs fine, on the same machine.
maybe there arent enough water pressure to sustain all the machines?