Reverse Osmosis Drinking Water in Fishers

An under-sink reverse osmosis system typically costs $300–$950 installed, and a whole-house RO system $4,800–$8,000 (HomeGuide). RO pushes water through a fine membrane that removes most dissolved minerals, including the sodium a softener adds and most PFAS, leaving low-mineral water for drinking and cooking.

What RO takes out

Citizens water averaged 44 ppm of sodium in 2025, with a range of 15 to 139 ppm, and 72 ppm of chloride (Citizens Energy Group). Indiana American's plants reported sodium of 36.1 to 92.7 ppm (Indiana American Water). A salt-based softener adds more sodium as it removes hardness. An RO membrane rejects most of it, along with the minerals behind cloudy ice cubes and kettle scale, and most trace compounds that make it through city treatment.

Under-sink or whole-house

Under-sink RO is the common choice: a compact unit with pre-filters, a membrane, a small storage tank and a separate faucet. Tankless models cost more but deliver faster. Whole-house RO treats every tap and needs a large storage tank and a pump. On treated city water it's rarely necessary, and it sends more water to the drain. It makes more sense for unusual water problems than for Fishers' ordinary hard water.

Pairing RO with a softener

In a Fishers home that softens, RO goes after the softener. Softened water is easier on the membrane, so it lasts longer, and the RO then strips out the added sodium for drinking water. Without a softener, water at 19 to 27 grains can scale an RO membrane quickly, so plan on more frequent membrane changes.

What to compare

• Testing to NSF/ANSI 58, and to NSF/ANSI 53 or 58 for PFOA and PFOS if PFAS matters to you.
• The waste ratio: how much goes to the drain per gallon produced.
• Filter and membrane costs; HomeGuide lists $20 to $100 for RO filters.
• Room under the sink and a spare faucet hole or countertop space.

For whole-home options alongside RO, see what water softeners cost in Fishers.

Upkeep

RO is not a set-and-forget appliance. Sediment and carbon pre-filters are usually changed once or twice a year, and the membrane every few years, sooner on unsoftened water. If the flow from the RO faucet slows or the water starts tasting of minerals again, a filter or membrane is due. Write the install date on the housing so the next change isn't guesswork.