What is wrong next to my home hose down filtration system? I've had sea filtration system (5 osmosis) installed about 3 years ago...

I've had sea filtration system (5 osmosis) installed about 3 years ago and be changing filter regularly. However, the amount water (has 5 gallon holding tank) coming out of the system have been shrinking. At first, I be able to take 3-4 gallons without losing river pressure without much of problem but immediately days, after 2 cups of water, just about any pressure left to capture anymore out of the tank. It literally drips..... After 10 minutes for recharge, it give 2 more cups and so on. What can be wrong with the system?? I've be maintaining and varying filters regularly but do not know what is wrong beside it. Any help will be appreciated.

TIA
Carrier Heat Pump doesn't blow hot nouns. ...
Answers:    Sediment, size or lime in the lines restricting flow. Or perchance you need a strange water pressure regulator.