Example: a year of drinking water for a family of four
Here is an illustration using stated assumptions. Your numbers will differ.
- Consumption: 190.8 gallons a year, which is four people at the U.S. average of 47.7 gallons of bottled water per person in 2025, per the same IBWA figures.
- RO filters and membrane: $40 to $90 a year for a standard filter set, plus a $30 to $100 membrane every 2 to 5 years, per Angi’s 2026 RO cost guide. We spread the membrane cost over its life.
- RO water use: 2.3 gallons (WaterSense level) to 5 gallons (conventional) sent to the drain per gallon produced, per EPA WaterSense, billed at LVVWD’s lowest and highest tier rates.
- Bottled prices: the per-gallon figures from the table above.
Under these assumptions, single-serve bottles run about $586 a year, cases about $361 and 5-gallon delivery about $305. RO operating costs land around $47 to $147, of which the tap water itself is only about $1 to $7.
RO does have an upfront cost. Angi lists $200 to $800 for an under-sink system plus $100 to $300 for installation. Against the case-price example, the yearly savings of roughly $214 to $314 would cover that in about one to five years, and faster if you would otherwise buy single-serve bottles. For local pricing, see our guide to reverse osmosis system cost in Las Vegas.
Example annual drinking water cost, family of four ($ per year)
Single-serve bottles (U.S. avg. price)
$586
Bottled water by the case (example price)
$361
5-gallon jug delivery (example price)
$305
Under-sink RO, high estimate
$147
Under-sink RO, low estimate
$47
Example assumptions, not quotes: 190.8 gallons/year (4 people x 47.7 gal U.S. per-capita bottled water, IBWA/Beverage Marketing Corp. 2025). Single-serve at U.S. avg. 2.4 cents/oz ($3.07/gal). Case: assumed $6 per 24 x 16.9 oz ($1.89/gal). Delivery: assumed $8 per 5-gal jug, excluding dispenser/delivery fees. RO: $40–$90/yr filters + $30–$100 membrane over 5 or 2 years (Angi 2026), plus 2.3–5 gal reject per gal (EPA WaterSense) at LVVWD $1.61–$6.33 per 1,000 gal. RO upfront cost ($200–$800 + $100–$300 install, Angi) not included.