Reverse Osmosis for Peoria, IL Drinking Water

An under-sink reverse osmosis system costs about $150–$1,300 and a whole-home system $1,000–$4,800 (This Old House). In Peoria, IL, RO usually goes in after a softener, where it cuts sodium, which already runs 36.5–91.4 ppm in the tap water (Illinois American Water 2025), and to reduce other dissolved minerals at the kitchen faucet.

Why RO pairs with a softener here

At 19 to 37 grains of hardness, a salt-based softener adds a noticeable amount of sodium on top of what's already in the water. An RO membrane rejects most dissolved salts, sodium included, so a softener at the main line and RO at the kitchen sink give you soft water for the house and low-mineral water for drinking and cooking.

Lead and nitrate, stated plainly

Illinois American Water reported that the Peoria system exceeded the lead action level in both 2025 monitoring periods, with a 90th-percentile result of 21 ppb against the 15 ppb action level. Lead enters from service lines and household plumbing, and the utility is adjusting corrosion control and replacing lead service lines (2025 Annual Water Quality Report). Nitrate ranged from 0.16 to 4.25 ppm, under the 10 ppm limit. If lead is your concern, choose an RO system whose NSF/ANSI 58 certification lists lead reduction, and use the utility's service line lookup.

Under-sink versus whole-home RO

Under-sink RO treats one faucet and sometimes the refrigerator line. Whole-home RO treats everything and costs far more to buy and run. On water this hard, a whole-home membrane needs softening ahead of it or it scales quickly. For most Peoria, IL homes, under-sink RO plus a softener is the practical setup.

Upkeep and running costs

An under-sink unit needs its sediment and carbon pre-filters changed on the maker's schedule, often every six months to two years, and a new membrane every few years. On softened water the membrane usually lasts longer, because hardness is what scales it. Installation for a typical system runs about $300 to $700, according to This Old House, with more for a refrigerator line or a tight cabinet. If the faucet slows to a trickle, the pre-filters are usually due.

What to compare

Look at the certification listing, the waste-water ratio, storage tank size, and the replacement schedule for filters and membrane; This Old House says membranes typically last three to five years. The Peoria, IL cost table shows RO next to softeners and filters.