Pure Water Filtration MI ›
Well Water Guide › RO System Not Working Michigan

Reverse Osmosis System Not Working? Michigan Well Water Troubleshooting Guide

By Kyle Wood, Water Treatment Specialist • Updated May 2026 •
Serving Brighton, Howell & Livingston County, Michigan

How a Reverse Osmosis System Works

An under-sink RO system has 3–6 filtration stages. Understanding the sequence helps you identify which stage is causing the failure:

Stage 1: Sediment pre-filter (5 micron). Removes particulate matter, rust, and sediment that would clog or damage the RO membrane. On Michigan well water with iron above 0.3 mg/L, this filter can clog in as little as 3–4 months.

Stage 2: Carbon block pre-filter. Removes chlorine (if present), chloramines, and organic compounds that degrade the RO membrane. Also reduces some dissolved organics that affect taste.

Stage 3: RO membrane. The core of the system. Forces water at pressure through a semi-permeable membrane with pores small enough to reject dissolved salts, nitrates, arsenic, lead, fluoride, PFAS, and most other dissolved contaminants. The rejected contaminants are flushed to drain as “concentrate” (wastewater).

Stage 4: Post-filter / polishing carbon. Removes any residual taste or odor from the storage tank. Provides final polishing before the water reaches the faucet.

Storage tank. A small pressure tank (2–5 gallons) stores filtered water under pressure for immediate delivery. The tank has an air pre-charge on one side of a rubber bladder that provides the pressure to push water out when the faucet is opened.

Problem 1: No Water or Very Slow Flow from the RO Tap

Check the supply valve first. The feed water shut-off valve under the sink (usually a needle valve on the cold water supply line) must be fully open. A partially closed valve reduces pressure to the system and dramatically slows or stops production. Turn counterclockwise to open fully.

Check the storage tank pressure. Shut the RO feed valve, open the RO tap, and let all water in the tank drain until flow stops. Close the tap. Locate the Schrader valve on the storage tank (usually on the bottom). Press the pin: you should get a short puff of air at 6–8 PSI (the standard RO tank pre-charge). If water comes out, the tank bladder has failed and the tank is waterlogged — replace the tank ($30–$60). If no pressure is present, add air with a bicycle pump to 6–8 PSI and see if production improves.

Check the feed water pressure. RO systems require a minimum of 40 PSI to produce water effectively; optimal is 60–80 PSI. Michigan wells with standard pressure tank settings (40/60 PSI) may drop below 40 PSI during peak demand (multiple fixtures running). Test pressure at the cold water supply under the sink with a pressure gauge during peak use. If pressure is below 40 PSI, the well pressure system needs attention before the RO can function correctly. See our guides to low water pressure from well Michigan and pressure tank replacement Michigan.

Clogged pre-filters. A severely clogged sediment or carbon pre-filter creates a pressure drop that prevents adequate feed pressure from reaching the membrane. Even if the supply pressure is 60 PSI, a clogged 5-micron sediment filter can drop pressure to 20–30 PSI by the time water reaches the membrane. Replace the pre-filters (both sediment and carbon block) and retest production.

Problem 2: Slow Production (Less Than 1 Gallon Per Hour)

RO systems produce water slowly under normal conditions — a typical residential RO membrane is rated for 50–100 gallons per day, or roughly 2–4 gallons per hour. This is normal. A full storage tank takes 2–4 hours to fill. Problems arise when production is substantially slower than rated or when the tank never fully pressurizes:

Low feed pressure. Every 10 PSI below the rated pressure reduces production rate by 10–15%. At 40 PSI feed (the minimum), a 75 GPD membrane may produce only 40–50 GPD. At 30 PSI, production may be so slow that the tank never fills before the next use. Installing a booster pump on the RO feed line (a small inline pump, $80–$150) raises pressure to 80–100 PSI and dramatically increases production rate.

Cold water temperature. RO membrane flux (production rate) drops approximately 3% per degree Fahrenheit below 77°F. Michigan groundwater is typically 48–52°F year-round, which reduces production rate to approximately 50–60% of the rated temperature specification. This is normal and expected — an RO rated at 75 GPD at 77°F actually produces about 40–45 GPD at Michigan groundwater temperatures. This is not a failure; it is the correct expectation for Michigan.

Fouled or expired membrane. An RO membrane that has been fouled by iron, calcium scale, or biological growth produces water much more slowly than when new. Michigan well water’s high iron and hardness are the two main membrane foulers. See the membrane section below.

Problem 3: Water Tastes Bad from the RO Tap

Post-filter needs replacement. The polishing carbon filter between the storage tank and the RO faucet is the most common cause of off-taste from a functioning RO system. This filter should be replaced annually. A carbon post-filter that has exceeded its capacity passes taste compounds from the storage tank without adsorption. Replace the post-filter and test the taste after the tank refills once.

Storage tank contaminated. If the RO system has been unused for several weeks, bacteria can grow in the storage tank. Sanitizing the system (a dilute bleach flush followed by thorough rinsing) resolves this. RO systems that will be unused for more than 2 weeks should be shut off, drained, and the filters removed.

Membrane producing low-quality water. A failed or degraded RO membrane allows contaminants through that it previously rejected. If the water tastes similar to unfiltered tap water, the membrane has failed. Test with a TDS meter: good RO water should be 5–50 TDS; incoming Michigan well water is typically 300–600 TDS. If RO water is above 100 TDS, the membrane needs replacement.

Iron or H&sub2;S in the feed water fouling the membrane. Michigan well water with iron above 0.3 mg/L will eventually foul the RO membrane with iron oxide. Iron fouling turns the membrane orange-brown and dramatically increases rejection pressure requirements. The correct approach is whole-house iron treatment upstream of the RO to protect the membrane. See our guide to iron in Michigan well water.

Michigan Well Water and RO Membrane Life

Standard RO membrane life ratings (2–5 years) assume chlorinated city water as the feed source. Michigan private well water is a more demanding environment:

Iron oxidizes on the membrane surface, reducing active membrane area and increasing operating pressure requirements. Iron above 0.3 mg/L should be treated whole-house before the RO.

Hardness (calcium and magnesium) precipitates as scale inside the membrane spiral when pH rises during concentration. Michigan’s typical 20 GPG hardness creates significant scaling potential on the reject side of the membrane.

Iron bacteria can colonize a membrane if iron and organic matter are present. Biological fouling creates a slime layer on the membrane surface and cannot be removed by chemical cleaning alone — membrane replacement is required.

H&sub2;S at elevated concentrations can degrade the polyamide thin-film membrane layer over time.

For these reasons, Michigan well water RO membranes in unprotected systems (no whole-house iron or hardness treatment upstream) typically need replacement every 12–24 months rather than the 2–5 year rating. Installing whole-house iron and hardness treatment upstream extends RO membrane life to the rated 2–5 years and dramatically reduces filter consumption.

Recommended Filter Replacement Schedule for Michigan Wells