How reverse osmosis drinking water works
A point-of-use reverse-osmosis system uses pressure and a membrane to separate treated water from concentrate sent to a drain. Reduction performance, water efficiency, pretreatment, storage, and maintenance vary by model, so compare the exact certified claims with the concern identified in your water.
What you'll learn
- How pressure drives water through an RO membrane
- Why an RO system produces both treated water and reject water
- How prefilters, postfilters, tanks, and pumps vary by model
- How to compare exact contaminant-reduction and efficiency certifications
- Why replacement intervals and performance checks come from the manufacturer
Step by step
- Use the serving utility's current report and appropriate testing to identify the treatment goal.
- Check the exact model's independently certified contaminant-reduction claims; an RO category label alone does not establish every reduction.
- Trace the model-specific flow path through its prefilters, membrane, storage or pump components, and postfilter.
- Compare treated-water production, incoming-water use, and reject flow using the same definitions and test conditions.
- For efficiency, verify the exact model. WaterSense-labeled point-of-use RO units meet criteria that include no more than 2.3 gallons of reject water per gallon treated under certification conditions.
- Replace cartridges and the membrane only on the manufacturer's schedule or specified performance indicators, and verify results as directed.
Filter and membrane life cannot be set from a generic calendar. Feedwater, use, pressure, pretreatment, storage design, and the exact model all matter. Slower output or changed taste can have several causes; follow the manual and test before choosing a replacement part.
Rather have a pro handle it?
Connect with a separately licensed water-treatment provider in San Diego County. Ask about the free in-home water test.
Keep learning.
How to test your tap water at home
The City of San Diego reports that drinking water in its system averages about 16 grains per gallon and varies by area and water demand. A home test strip can provide a quick screening result for the measures listed on that kit, but it does not replace a laboratory analysis or establish that water is safe.
How to spot hard water in your home
Hardness minerals are not obvious from the water's smell or appearance, but scale, spotting, and changes in soap lather can provide useful clues. Those signs can have other causes, so confirm hardness with an appropriate test before choosing treatment.
How a whole-house water filtration system works
A point-of-entry water-treatment system is installed on the line serving the home, so the fixtures downstream receive treated water. What it reduces depends on the exact equipment, media, flow conditions, and certified claims. Understanding that scope helps you compare a whole-house system with a point-of-use device at one tap.