Reverse Osmosis Systems in Yuma, Arizona

The City of Yuma says a reverse osmosis system is designed to remove 90–95% of the minerals in tap water. An under-sink unit runs about $150–$1,300, and whole-house RO $1,000–$4,800 (This Old House). In Yuma, RO mostly serves the kitchen tap, where it lowers sodium and minerals.

What the city says about RO

The city's FAQ is refreshingly neutral. It says RO removes most minerals, that many people equate that with better taste, and that whether it's worth the cost is a matter of preference. It also reminds owners that pre-filters and carbon filters don't last forever and may need changing as often as monthly (City of Yuma Water FAQs). That upkeep is the real cost of owning RO.

Sodium before and after softening

Yuma's water measured 110 ppm sodium at both plants in 2025, and the FAQ gives a range up to 250 mg/L from Agua Viva when groundwater is in the blend. A salt-based softener adds to that. An RO membrane rejects most dissolved salts, so a softener for the house and RO for drinking and cooking is the standard pairing.

Under-sink or whole-house

An under-sink system treats one faucet, sometimes plus the refrigerator. Whole-house RO treats every tap, costs far more, needs a large storage tank and pump, and sends a steady stream of concentrate to the drain. On 18 to 22 grain water it also needs a softener ahead of it to keep the membrane from scaling. For most homes here, under-sink is the practical choice. Check before buying that the cabinet has room for the tank and that the sink has a spare hole, or a spot for one, for the separate faucet.

Choosing and caring for a system

• Check the NSF/ANSI 58 listing and what contaminants it names.
• Compare waste-water ratios; in a desert city, efficiency matters.
• Plan for pre-filter and carbon changes, and a membrane every three to five years (This Old House).
• Expect installation of about $300 to $700 for a typical system (This Old House).

Prices sit alongside softeners on the cost of a water softener in Yuma page.