We recommend calling us to schedule proper annual maintenance, which includes testing your membrane for TDS reduction and sanitizing your system, but if you are handy and want to do the job yourself, just follow these instructions for ordering online. If you have any questions, call us at 855-3M-Water. Below are filters you are due to replace. Simply click on either of the two then choose add to cart. The other filter will appear under “YOU MAY ALSO BE INTERESTED IN...” Add it to your cart and proceed to checkout.