Almost every resurfacing, tile or remodel job begins by draining the pool. In Central Florida, that step deserves more planning than it gets, because of how much rain falls in summer and because Orange County has specific rules about where pool water may go. This guide pulls together what the trade press, NOAA and Orange County say, so you can talk timing and discharge through with the contractor you hire.
One legal point first: under Fla. Stat. §489.105(3)(l), the swimming pool/spa servicing license covers “the substantial or complete draining of a swimming pool… for the purpose of repair or renovation.” Draining for a resurface is licensed pool work, which our guide to who can resurface a pool in Florida explains.
Hydrostatic pressure: what the trade says
A pool shell sits in the ground with groundwater around it, and draining changes the forces on it. No Florida agency guidance on this was found; the advice below is trade practice, not law.
AQUA Magazine, in its article “Pressure Points,” explains that an influx of groundwater raises “exterior hydrostatic pressure [that] will cause the pool to crack, bulge, or float.” A hydrostatic relief valve is one safeguard, not the whole answer. WaterShapes, in an article by Eric Herman, notes that “the notion of a hydrostatic relief valve as a cure-all is also off the mark.”
The practical takeaways the trade sources point to are simple:
- Avoid draining during or right after heavy rain.
- Keep the time the pool sits empty as short as the work allows.
- Confirm the contractor checks the hydrostatic relief valve and local groundwater before draining.
The U.S. Geological Survey notes that surficial-aquifer water levels in Orange County “fluctuate… from seasonal and annual variations in rainfall,” which is why the calendar matters.
The rainy season and the October–May window
NOAA’s 1991–2020 climate normals for Orlando International Airport show how lopsided the year is:
- Annual rainfall averages 51.45 inches.
- June through September brings 29.57 inches, about 57 percent of the year.
- June is the wettest month at 8.05 inches; November is the driest at 1.79 inches.
- The airport averages 15.0 days a year with an inch of rain or more.
Those one-inch days cluster in summer: 1.8 to 2.5 a month from June through September, compared with 0.5 to 1.4 a month from October through May. Central Florida also sees 80–100 thunderstorm days a year (NWS Melbourne puts interior Central Florida at 80–90; the Florida Division of Emergency Management says “nearly 100 plus”).
That is why many owners aim for the October–May window. New finishes need dry application days, and the summer months are when heavy rain and high groundwater are most likely. Owners who want the pool ready for the hot season also have a reason to plan ahead: Orlando averages 109.9 days a year at or above 90 °F, jumping from 3.6 such days in April to 13.6 in May.
What Ian and Milton showed
Two recent hurricanes show how much rain can arrive at once. During Hurricane Ian, the Orlando-area threaded record (NOAA ACIS) logged 13.11 inches on September 28–29, 2022. During Hurricane Milton on October 9–10, 2024, NWS Melbourne reported a 76 mph gust at Orlando International Airport and 14.83 inches at the Orlando West cooperative observer gauge.
The takeaway is not alarm but planning: an empty pool during storm season is a scheduling choice worth avoiding. Orange County also advises owners to “STOP adding chlorine or salt several days before a pending storm,” because storms “can significantly increase the volume of water in your pool which may result in your pool overflowing.”
Orange County’s discharge rules
Orange County’s pool pollution prevention page sets out how pool water may be released. Violations fall under the county’s illicit discharge rules (Code ch. 15, art. IV). The main points:
- Stop chlorine first. Stop adding chlorine or salt several days before draining. The county says “in general, 10 days is adequate to dissipate chlorine.”
- Test before you release. Total chlorine should be 0.01 mg/L (ppm) or less and pH between 6.5 and 8.0. The county mentions sodium thiosulfate to neutralize chlorine and soda ash to raise pH.
- Lawn only, slowly. Discharge to the lawn at a recommended 25 gallons a minute or less.
- Never to storm drains or streets. “Never create a direct connection between the pool water and a storm drainage system, the streets, gutters, inlets, ditches, stormwater ponds, wetlands, or waters of the County.”
- Never to septic. “Never drain pool water to a septic tank or drain field.”
- Neglected pools are pumped out. For contractors hired to repair or resurface a neglected or unmaintained pool, a sanitary disposal service must pump out water contaminated with algae, debris or metals.
The same page notes that discharges directed to the county’s storm sewer system need a County Right-of-Way Utilization permit, and that building permits apply to new pools and modifications of existing pools.
A note on muriatic acid
Acid washing and etching can involve muriatic acid. Orange County warns that “muriatic acid used for etching the concrete pool interior will reduce the pH rapidly. A low pH will immediately kill plants and animals.” The county’s pH range of 6.5 to 8.0 for lawn discharge still applies, so ask the contractor how acid-wash water is neutralized and tested.
Dewatering and the water management district
Some jobs pump groundwater as well as pool water. Orange County’s page says “discharging groundwater or existing pool water from dewatering operations may require approval from the State,” and lists the St. Johns River Water Management District (SJRWMD, 1-800-451-7106). If your project involves dewatering, ask the contractor whether SJRWMD approval applies.
City and town rules
Cities and neighboring counties set their own rules. In Windermere, for example, the town has said homeowners “are responsible for violations that occur on their property; enforcement and fines could result from illicit discharges.” We saw that wording only in a search summary of a town page, so check the Town of Windermere’s current guidance before you rely on it. See our Windermere page for more local notes.
Permit rules for resurfacing vary by city and county, and no Orange, Seminole or Lake county source we found states the residential rule in writing. Orange County has treated pool resurfacing as a pool renovation, and it requires a permit for new concrete or paver decks (pavers need a zoning permit). The licensed contractor confirms and pulls any permit required.
Questions to ask before the pool is drained
- When will you drain, and how long will the pool sit empty?
- Will you check the hydrostatic relief valve and groundwater first?
- How will you test chlorine and pH, and where will the water go?
- If the water is green or dirty, who pumps it out?
- Who pays for refill water? (On OUC water, a 20,000-gallon refill adds roughly $47–$84 in volume charges before sewer, depending on that month’s use. See our Orlando cost guide.)
The resurfacing process page walks through what typically happens after the pool is drained. We connect Orlando-area homeowners with independent local pool contractors for free, no-obligation quotes. The contractor you choose quotes, contracts and does the work. Request a free quote and plan your drain for the drier months.
Frequently asked questions
When is the right time to drain a pool in Orlando?
Many owners aim for October through May. NOAA normals for Orlando International Airport put about 57 percent of the year’s 51.45 inches of rain in June through September, and one-inch rain days drop to 0.5 to 1.4 a month outside those months. Trade sources advise against draining during or right after heavy rain, and the contractor should check groundwater first.
Can I drain my pool into the street or a storm drain?
Not in Orange County. Its pool pollution guidance says never to connect pool water to a storm drainage system, streets, gutters, ditches, stormwater ponds or wetlands, and never to drain to a septic tank. Water that meets the limits goes to the lawn at 25 gallons a minute or less. Contaminated water from a neglected pool is pumped out by a sanitary service.
What chlorine and pH levels does Orange County require before draining?
Orange County says total chlorine should be 0.01 mg/L (ppm) or less and pH between 6.5 and 8.0 before discharge to a lawn. It suggests stopping chlorine or salt several days ahead, noting that 10 days is generally adequate, and mentions sodium thiosulfate to neutralize chlorine and soda ash to adjust pH. Ask your contractor how they test.