The manufacturer 3M advises every six months -- which is optimal. In many cases probably once a year is also adequate. Correct replacement frequency in fact depends upon three main factors:

(1) quality of water being filtered,
(2) filtered water quality you want to maintain,
(3) usage -- specifically, how many gallons of water are being filtered on average per day., month etc.

Thus there is no universally right answer, just as if you had to answer how often you replace the bag in your vacuum cleaner. The answer is... it depends on factors that are inherently variable.

In many applications, you'll notice a reduction in flow rate or pressure out of the filter incrementally over time. This is especially likely to be the first and primary indicator in New York City -- Manhattan above all -- where the water is unusually turbid. In other words, the more particles are being captured by the filtration media, the faster the media will become saturated which in turn causes pressure loss.

Loss of pressure or reduction of flow rate does not necessarily mean a loss of product water quality. In fact, the more contact time there is between water and filtration media, the better the quality of filtration. But at some point that stops being applicable, and the inconvenience of reduced pressure indicates it's time to replace the cartridge.

You won't need to hire outside service or even any tools. The cartridge twists a 1/4 turn out and the new one in reverse. Keep your cold water off of course. Inside the head assembly for the XL7000 there is a built-in shutoff valve. Instructions are on the cartridge label and also at

https://betterwaters.com/products/xl-7000-water-filtration-system. Scroll down to Product Documentation.

For the CX9000 and TX9000 the procedure is the same, but for these models the head assembly does not have a shutoff valve within, so just be sure to shut the nearest cold water valve and keep it closed until it's time to introduce water into the new cartridge.

Once you turn on the water to fill the new cartridge keep in mind it is purging out air, so the flow will be uneven for a few seconds and noisy. It's normal. Keep the water flowing into the cartridge for 3 minutes nonstop. The product water is good to drink, but the uninterrupted introduction of water helps pressurize the membrane inside for maximum longevity.

We cannot claim or quantify reduction of PFOA/S the same way we do for other contaminants, as the XL7000 has never been submitted to NSF for specific Standard P473 reduction of PFOA and PFOS. It may very well be submitted next year (2024). In the meantime, since the media of choice for PFOA/S reduction is activated carbon, and there is an abundant amount of activated carbon in the XL7000 (and the TX9000 too with respect to its size and rated flow rate), we think it is a safe bet that the XL7000 and TX9000 do an excellent job at reducing PFOA/S. Note that not everything a filter takes out is reportable or can be claimed at the same level of certainty. Note as well that whether this is a concern should also depend on the source of your tap water. New York City water e.g. doesn't have PFOA/S because it originates from protected reservoirs.

That one's easy: No.

Yes. The XB7000 was discontinued by 3M some years ago. We had a large inventory for years that we were able to continue supplying from, but no longer. The XL7000 fits into the same head, so all you need to do is order the XL7000 cartridge and it will fit exactly the same. The XL is a much more comprehensive filter than the XB, which is why the factory decided it was redundant. Note: The XL cartridge is about 3" taller than the XB, so be sure you have adequate clearance if you are retrofitting an XL7000 cartridge into an XB7000 head.

Glad you asked! We've written a post to try to offer clarity about just what NSF assures, and how it functions. Here.

Yes the filter includes carbon block. The filtered water will not, as a practical matter, corrode copper pipe. (We can't say "never" because after a million years, water will corrode anything...) If your concern is corrosion there is no threat at all. The filter leaves the mineral content of water intact -- if you were running distilled water or even reverse osmosis through copper, that would over time definitely have a corrosive effect. But not filtration alone.