The operating cost categories
| Category | What it is | What drives it |
|---|---|---|
| Pre-filters | Sediment and carbon stages that protect the membrane | Particles and chlorine or chloramine load, gallons used |
| RO membrane | The core stage | Water hardness and TDS, pre-filter upkeep, use |
| Post and remineralization stages | Polishing and, on alkaline models, mineral addition | Gallons used, model design |
| Drain water | Concentrate sent to drain | System efficiency rating, water pressure |
| Electricity | Only on pumped or tankless units | Model |
| Sanitizing and service | Periodic cleaning of housings and lines | Manufacturer recommendation |
Maintenance that protects the membrane
The membrane is usually the most valuable consumable. It depends on the pre-filters: if sediment and carbon stages are left too long, the membrane works harder and can wear sooner. That is why keeping to the pre-filter schedule is the cheapest way to keep RO running well.
- Change pre-filters on schedule, not when taste changes.
- Watch for slower flow at the faucet; it can mean filters are loading up.
- Ask how pressure in your home affects performance.
Drain water: the hidden operating cost
RO works by pushing water through a membrane and flushing the rejected portion to drain. The ratio of drinking water to drain water varies by model and pressure. Ask for the model's rated efficiency, then factor it into your water bill. Newer designs vary considerably here, so it is a fair comparison point.
A simple yearly routine
- Put each filter's change date on your calendar the day it is installed.
- Keep a spare set of pre-filters on hand so a change is never delayed.
- Sanitize housings when the manufacturer recommends it, usually at a filter change.
- Check the faucet flow and the tank fill time now and then.
- Look under the sink for drips at each change.
A routine like this keeps operating costs predictable and the membrane working as designed.
Questions to ask before you buy
- What is the replacement schedule for each stage, for a household like mine?
- Can I change the filters myself, or is a visit recommended?
- What is the model's rated efficiency and production rate?
- Is the system certified under NSF/ANSI 58, and which reduction claims are on the listing?
- Does the unit need electricity?
- What does the warranty cover, and does it require using specific replacement filters?
Living Water offers an alkaline reverse osmosis system with a dedicated faucet. See RO filter replacement cost for the filter side in detail.
Tank vs. tankless operating differences
Tank systems store treated water and generally run without power; tankless systems make water on demand and usually need electricity. Each has different maintenance points. Read tankless vs. tank RO before deciding.
Updated 2026-10-17 · Living Waters · Jorge Canela, Water Quality Specialist