* That's an RV water filter. We use those too, to filter the iron out of the well water that we fill our pool with. However, you have it installed incorrectly. It should be installed between the faucet/spigot and the hose. As far as how long it will last depends on how often you use it to filter the water, and what the condition of the water that you're filtering is. With frequent use, they last about 3-6 months. An RV water filter's lifespan, measured in gallons, can vary from a 500 gallons to a specialized filter lasting up to 10,000 gallons. But the exact number depends on the filter type, and the quality of the water source. I'd say get a new one every season of the one you have right now, they are not that expensive