How to Replace Water Softener Resin

Signs the resin is spent

Resin beads wear out slowly, and the valve and tanks can usually be reused. Penn State Extension notes that some resin cannot be washed clean of contaminants and has to be replaced, and that red, oxidized iron (iron exposed to air or chlorine) clogs it.

Worn or fouled resin usually shows up as:

• Hard water that no setting fixes. The softener regenerates and uses salt, but softened water still tests hard. Compare raw and softened water side by side, as described in how to test water hardness.
• Falling water pressure. SoftPro lists fouled resin and escaped beads among the causes of pressure loss through a softener.
• Beads in the plumbing. Small dark round beads in aerators or showerheads point to a cracked distributor or damaged screens. SoftPro describes the beads as about 0.3 to 1.0 mm. See resin beads in water before you buy resin, because a broken distributor has to be replaced too.

Most hard-water complaints are not the resin. The Fleck 5600SXT manual's checklist for hard water starts with simpler causes: the bypass left open, no salt or a salt bridge, a wrong hardness setting, a plugged injector screen, a short brine fill time, hardness left in the water heater, a leak at the distributor tube, or worn valve seals. Work through the troubleshooting guide and try a resin cleaner if iron is the issue. Replace the resin only when those come up clean.

How much resin to buy

Buy the same amount of resin the tank holds now. It is listed in cubic feet on the tank label, in the manual or on the original order. If you only know the grain rating, Pentair's 5600SXT manual gives a guide to how the two line up:

Other makers rate differently, so treat the table as a guide and trust your own label first.

Next, pick the resin type for your water:

• City water with chlorine. SoftPro's store text recommends 10% cross-linked resin for chlorinated water. SoftPro sells Aldex Premium 10% cross-link resin (sold by SoftPro, our store) for re-bedding a softener on city water, from $132.55 (October 2026).
• Well water with iron. SoftPro sells fine mesh resin for well water with iron (sold by SoftPro, our store), which the store describes as designed for well water and effective at removing iron, from $193.33 (October 2026). Oxidized iron, iron bacteria and higher iron still need an iron filter first.

If your tank uses a gravel under-bed, plan to replace that too. SoftPro's premium bedding gravel (sold by SoftPro, our store) comes in a 12-lb bag for the support layer under the resin, from $23.00 (October 2026); the store says it promotes correct flow and water distribution. A wide funnel makes the pour cleaner: SoftPro's resin and mineral tank funnel has a 10-inch opening that narrows to 2.5 inches.

Removing the old resin

The exact steps depend on the valve and tank, so keep your valve's service manual open. The general order is:

1. Bypass the softener. Put the bypass valve in bypass so the house keeps running on hard water. See the bypass valve guide for each type of handle.
2. Relieve the pressure. In the Fleck service steps, you briefly advance the control to Backwash and then return it to In Service, which bleeds off pressure.
3. Unplug the valve. Never open a valve that still has power.
4. Disconnect the plumbing. Undo the bypass or connectors from the valve, the drain line and the brine line, and label which is which.
5. Take the valve off the tank. Lift the valve and distributor tube clear of the tank.
6. Empty the tank. Remove the old resin and any gravel into buckets, and check the distributor and its screen for cracks. Dispose of the old media as your local rules allow.

If you are unsure about any connection or the tank is too heavy to handle, a licensed plumber can do the job.

Refilling and restarting

1. Seat the distributor tube. Stand it in the center of the tank. The Fleck manual says the distributor tube should be cut to the dimensional drawing or flush with the top of the tank.
2. Add gravel, then resin. Pour the under-bed gravel first if your tank uses it, then the resin, through a funnel.
3. Fit the valve. Lubricate the distributor and tank O-rings with 100% silicone lubricant only, never petroleum grease, as both the Fleck and Pentair manuals say, and thread the valve on by hand.
4. Fill slowly. Pentair's manual says not to open the water valve fully when filling the media tank, so the media does not leave the tank. Open the bypass a little at a time.
5. Run the start-up your system calls for. In the Fleck and Pentair manuals, a new bed gets a manual pass through every step: a backwash lasting 10 minutes of steady drain flow (or until the water clears), a brine draw that continues until brine is pulled from the tank, a rapid rinse of 5 minutes or until clear, and finally brine fill. SoftPro and Quality Water Treatment, by contrast, ship their systems with pre-charged resin and skip the first regeneration, so check which applies to the resin you bought.
6. Check for leaks and reset the clock. Check the seals, then confirm the time and hardness settings in the settings guide.

Quality Water Treatment notes that if pressure drops badly at first start-up, a backwash can reclassify the media. Afterward, keep the new bed healthy with a yearly maintenance routine.

Common questions

Before and after a re-bed

• MaintainUsing a resin cleaner
• MaintainSoftener maintenance, month by month
• FixResin beads in water
• SettingsWater softener parts explained
• MaintainHow to drain a water softener