The Pur Advanced 3-Stage faucet-mounted water filter is a great option for most homes. More than that, it’s excellent for apartments, rentals, and offices, where a custom installation process might not be a possibility. The downside of the filter is that its small RF-9999 filter insert is only rated for 2-3 months of use and 100 gallons of water, which means you’ll be changing the filter fairly regularly.

Pur Advanced Water Filter from Amazon.com

Before even getting started, make sure you are buying new RF-9999 filters in multi-packs You’ll save a lot of money by buying more than one at once. In fact, if you buy a 12-pack, you’ll be spending just $7 per filter, where a single filter sold on its own can cost up to $14.

Swapping out a new filter for an old one is brief process, but it’s worth knowing how to do it properly.

Clean your hands thoroughly!
Grip the bottom of the filter and twist the top of the cylinder. This will remove the lid piece.
While maintaining your grip, twist and slightly wiggle the blue refill piece in order to pull it out of the housing.
Throw our or recycle the used refill. It can’t be cleaned or reused.
Inspect the inside of the filter for debris, dirt or mold. Give it a wipe down with a clean lint-free rag and possibly soapy water or a vinegar solution. Give it a good rinse.
Do the same with the entry point for the water. This area can a bit gross as it’s a natural collection point for any junk in your not-yet-filtered water.
Get a RF-9999 refill cartridge and remove it from the sealed foil wrapper. This will likely require scissors.
Push the refill into the filter. It will only fit one way, so don’t force it.
Twist the lid piece back in place. Make sure it’s a secure fit and tightly closed.
Run the water on cold for 5 minutes to remove any manufacturing dust from the filter. Don’t worry if the flow is slow at this point, it will improve with time.

How Do I Know if My Filter Should Be Replaced?

This isn’t always as simple as it seems. This is mainly the case because the 2-3 month number is a suggestion based on average debris levels in water, not a rule. The filter has an LED indicator that will turn from green to yellow and then ultimately red when your filter need to be swapped out, but this isn’t totally reliable. The LED indicator is more of a reminder than it is a definitive guide.

Keep in mind that a filter’s job is to remove contaminants from your water that shouldn’t be there. If the filter’s flow rate slows down rapidly it’s extremely like that it’s not a defect with the filter, but rather that there are contaminants in your water. These might be harmless or they might not, but the filter will remove everything is can regardless.

There are a number of factors that can affect the contaminant levels in water, causing them to spike periodically. One major one that is not obvious is construction in your area. Construction, particularly in cities, can cause movement in the pipes which raised sediment and will send more total dissolve solids (TDS) to your faucet.

The Pur’s water flow will slow down dramatically with time. Here’s an example of what diminished flow will look like. If it gets super slow, your cartridge needs to be replaced! This is more a practice concern than a safety one, as the filter will still do its job, but eventually the filter will be overwhelmed with captures contaminants and it’ll have to be replaced, regardless of your tolerance for how slowly your water bottles are filled.

Pur Advanced Water Filter from Amazon.com

Do you have a Pur but are considering another options? Here’s a guide explaining the best way to pick a water filter for you.