The very design of the water filter means that it will eventually clog. Remember, it's not killing those creepy crawlies in the water; it's trapping them in the filter, where they remain. The first sign that your filter may need some maintenance is that it becomes difficult to pump. Don't force the issue. If you try to force the water through the pump, you may wind up with microscopic bugs in your water supply.
To get the longest life out of your water filter, it's important to follow the manufacturer's instructions on care and maintenance. But there are some general tips to keep in mind. You can count on filtering about 100 gallons of water before your water filter needs to be changed. Proper care and a little preventative maintenance will go a long way in reaching this goal.
You can scrub some water filters to clean them. If your filter is one of these, scrub it gently with a toothbrush when it becomes difficult to pump. If your water filter cannot be scrubbed, it may still be possible to clean it. Some water filters can be immersed in clean water and rinsed gently. Of course, this is something that must be done at home with clean tap water.
If your water filter comes with a pre-filter, be sure to use it. A pre-filter captures some of the larger debris before it enters the main filter. If your water filter doesn't have a pre-filter, and the water around you has a lot of sediment, make your own, using a coffee filter or clean shirt.
Some filters can be backwashed. To backwash your filter, remove the intake hose and reattach it to the filter outlet. When you pump water with the hose attached this way, it will send clean water through the filter, loosening debris that may be clogging it up. It's important to sanitize the filter with a solution of one capful of bleach to one quart of water before using it again. Pump the solution through the filter and let it dry thoroughly before storing it away or using it.