Pool water recycling San Diego: recycle or refill?

What pool water recycling actually does

Mobile reverse osmosis circulates water through external membranes and returns treated water while the pool stays full. A trailer-mounted system creates a temporary treatment loop: one hose pulls water in, another sends treated water back. The membranes target dissolved buildup that ordinary filters can’t catch, including calcium hardness, total dissolved solids, salts, phosphates, and cyanuric acid.

This isn’t routine cleaning. It doesn’t remove algae, fix leaks, repair equipment, or restore worn plaster. It solves one specific problem: water that looks clear but carries a heavy dissolved load from evaporation and stabilized chlorine use.

Why San Diego pools accumulate dissolved solids

San Diego’s water is hard. Every time water evaporates, it leaves dissolved minerals behind. The pool looks fine, maybe even sparkles, but calcium and salts keep climbing. Stabilized chlorine adds cyanuric acid with every dose. Over a season or two, those numbers creep past the range where chlorine works efficiently.

Testing reveals the problem. Clear water can carry high calcium, elevated salts, excess phosphates, and CYA levels that make sanitizing sluggish. If your test kit shows numbers climbing despite balanced chemistry, the water itself may be the issue.

For more on how hard water affects local pools, see our guide on hard water and San Diego pools. If cyanuric acid is your main concern, this post on high CYA walks through the options.

Recycling vs. draining: how to decide

Recycling fits when the water is clear but chemically overloaded. The shell stays full, the finish stays submerged, and only the reject stream (roughly 15% to 25% of total volume) goes to an approved wastewater route. The rest returns to the pool, cleaner than before.

Draining fits when RO can’t solve the problem. If the finish is failing, if the pool needs resurfacing, or if the water is green and full of suspended solids, draining may be the right move. An empty pool also aligns with planned finish work.

One rule applies to both paths: algae must be cleared first. RO doesn’t remove algae or suspended particles. If your pool is green, that is a different first step. Our post on green pool cleaning covers what that looks like.

A falling waterline is another signal to pause. If the level drops faster than evaporation explains, you may have a leak. Get leak detection before spending money on water treatment.

San Diego discharge rules you need to know

San Diego County Water Authority has 22 member agencies, and each property follows its local agency’s rules. The City of San Diego’s Municipal Code sections 43.0304 and 43.035(e)(3) ban pool water in storm drains. That isn’t a suggestion. Violations carry penalties.

For nonsaline discharge, the city requires:

• Dechlorination before release
• pH between 7 and 8
• Temperature matching ambient conditions
• No algae, algaecides, debris, or suspended solids
• A swept flow path with documented compliance

Salt pool water is banned from gutters and storm drains entirely. The only exception is a narrow direct route to a naturally saline water body. Sewer discharge needs Public Utilities Department approval. Landscape irrigation is allowed if there is no runoff or erosion.

Oceanside, Vista, Encinitas, and La Mesa set their own stormwater rules. If you live outside the City of San Diego, check with your local agency before routing any water.

Overfilling is also prohibited under Municipal Code section 67.3803(e). Controlled filling and active water-level monitoring are required when adding fresh water.

What recycling costs in San Diego

Portside Pool Purification’s published San Diego price, reviewed in August 2026, is $800 for pools up to 20,000 gallons. Larger pools cost more because additional volume means more membrane processing time. Their trailer processes up to 30,000 gallons in 24 hours, and most residential pools take 12 to 16 hours.

Drain-and-refill cost depends on your local water rates. City of San Diego single-family rates effective January 2026 are $8.51 per HCF for the first tier, $9.50 per HCF for the middle tier, and $11.89 per HCF above that. One HCF equals 748.05 gallons. Sewer charges are separate from the water bill.

A cheaper water bill doesn’t always mean a cheaper overall project. Recycling preserves water but costs more in treatment. Draining uses less specialized equipment but consumes a full pool’s worth of fresh water plus sewer fees. Properties outside City limits need their own district’s rates.

The matched pro quotes the full scope before work starts. Pool volume, finish condition, access, and equipment all shape the final number.

What RO won’t fix

This matters because homeowners sometimes expect recycling to solve problems it was never designed for.

RO treats water, not plaster. The membranes operate outside the shell. They don’t grind, wash, coat, or resurface anything. They won’t strip scale from tile, fill cracks, smooth rough areas, or restore a worn surface.

If your finish is peeling, has exposed aggregate, or simply can’t be cleaned, that is a resurfacing conversation. Our post on pool resurfacing options covers what is available.

Similarly, RO doesn’t fix broken equipment or plumbing. If your pump, filter, or heater is the problem, that is a repair job, not a water treatment job.

Post-treatment chemistry

After recycling, the water comes back with a different mineral profile. You need to rebalance before normal use.

The CDC recommends pH between 7.0 and 7.8, with at least 1 ppm free chlorine. If cyanuric acid or stabilized chlorine is present, aim for at least 2 ppm. Chlorine kills germs more slowly above pH 7.8, and below 7.0 it can corrode pipes and equipment.

Test chlorine and pH before swimming. The pro who runs the RO unit should provide post-treatment testing, but you will want to confirm the numbers yourself over the following days.

For a full breakdown of what to test and why, see pool water testing: what to test.

When to call us

If your test results show dissolved solids climbing, if you are unsure whether to recycle or drain, or if you need help navigating discharge rules, a licensed pool professional can assess the situation and route the water correctly. Call us at (858) 400-4404 and we’ll connect you with a licensed local pool specialist.

Frequently asked questions

Is pool water recycling the same as draining?

No. Mobile reverse osmosis circulates water through external membranes and returns treated water while the pool stays full. Draining empties the shell entirely and sends the full volume to an approved destination.

How much does pool water recycling cost in San Diego?

Portside Pool Purification's published San Diego pricing, reviewed in August 2026, is $800 for pools up to 20,000 gallons. Larger pools cost more because additional water requires more membrane processing time.

Can reverse osmosis remove algae from a pool?

No. RO membranes target dissolved substances like calcium, salts, and cyanuric acid. They do not remove algae or suspended solids. Water must be clear before treatment begins.

Can I drain my pool water into the storm drain?

No. San Diego Municipal Code prohibits pool water and backwash in storm drains. Nonsaline discharge requires dechlorination, a pH between 7 and 8, and matching ambient temperature before it can go to an approved route.

Does recycling fix a rough or damaged pool finish?

No. RO treats the water, not the plaster or pebble surface. It does not grind, wash, coat, or resurface anything. Worn or damaged finishes need a separate inspection and repair.