A whole house reverse osmosis system — also called a point-of-entry (POE) RO system — treats all the water entering a building before it reaches any fixture. Unlike under-sink units that protect a single tap, POE RO covers showers, laundry, dishwashers, ice makers, and every cold and hot water outlet simultaneously. AMPAC's whole house RO line is built for residential and light commercial buildings where source water TDS, hardness, or contamination levels make partial treatment inadequate.
Who Needs Point-of-Entry RO
The short answer: anyone on well water, agricultural-area groundwater, or municipal supply with TDS consistently above 500 mg/L. High TDS does not just affect taste — it accelerates scale buildup in water heaters, shortens appliance life, leaves residue on shower glass and fixtures, and can push sodium or nitrate levels into ranges that matter for infants and immunocompromised household members. Under-sink RO handles drinking water; whole house RO handles the rest.
Well Water vs City Water: Which Treatment Do You Need?
| Source |
Typical Concern |
Recommended Approach |
| Municipal (city) water |
Chlorine, disinfection byproducts, moderate TDS (150-400 mg/L) |
Carbon filtration + under-sink RO for drinking; softener for hardness |
| Private well water |
High TDS, iron, hardness, nitrates, bacterial risk |
Full pre-treatment train + whole house RO system |
| Agricultural-area groundwater |
Nitrates, pesticide runoff, high TDS, arsenic |
Whole house RO with iron and nitrate-specific pre-treatment |
| Coastal or brackish well |
Chlorides, high TDS (1,000-3,000 mg/L) |
Brackish-rated whole house RO at higher operating pressure |
Sizing Your Whole House RO System
General sizing rule: plan for 75-100 GPD per person for drinking and cooking needs, then multiply by 3-4x for whole-house coverage (showers, laundry, appliances). A 3-4 person household typically needs 300-500 GPD minimum; larger homes with irrigation or multiple bathrooms benefit from 750-1,000 GPD systems. AMPAC's whole house RO units are available from 300 GPD through 1,500 GPD in residential-rated configurations, with larger custom systems for estates and light commercial buildings.
Pre-Treatment for Well Water
Well water with iron above 0.1 mg/L, hydrogen sulfide, or biological contamination requires treatment upstream of any RO membrane. A standard pre-treatment train for whole house RO includes sediment filtration (25 micron to 5 micron), iron/manganese removal if indicated by water test, water softening for hardness above 7 gpg, and carbon block filtration before the RO membranes. AMPAC can specify a complete pre-treatment package matched to your water test results — contact our engineering team with your water analysis report and daily usage estimate for a system recommendation.
Every AMPAC whole house RO system uses FILMTEC membranes, ships factory-tested from Pomona, CA, and is backed by a 2-year parts warranty.
