FL Groundwater Temps: South FL 73°F avg → ΔT ~47°F to 120°F | Central FL 70°F → ΔT 50°F | North FL 67°F → ΔT 53°F | Panhandle 65°F → ΔT 55°F
Rule of thumb: 1 GPM requires ~2,100 BTU/hr for each °F of temperature rise (1 GPM × ΔT × 500 × 8.33 ÷ 60 × efficiency)
📋 FL Water Conservation Compliance
FL Showerhead Flow Limits (FPC 604.4)
Fixture
Max GPM (FL)
WaterSense
IECC Resid
Showerhead
2.0 GPM @ 80 psi
1.5–1.8 GPM
2.0 GPM
Body spray
0.5 GPM each
0.5 GPM
—
Handshower
2.0 GPM @ 80 psi
1.5 GPM
2.0 GPM
Bathtub filler
4.0 GPM
—
4.0 GPM
Multiple showerheads
2.0 GPM total
Per FPC exception — see note
FPC 604.4 Exception: Where more than one showerhead is controlled by a single valve, the aggregate flow rate of all heads shall not exceed 2.0 GPM at 80 psi unless each outlet has a separate shutoff — then each outlet is rated individually.
Body Spray Exception: FPC Section 604.4.2 — each body spray panel outlet rated individually at 0.5 GPM max. A 16-jet panel = 8.0 GPM aggregate is code-compliant if each head is ≤0.5 GPM.
County Water Conservation Ordinances
Select a county to see local water conservation rules.
Permit Requirements — FL Master Shower
When a permit IS required (FBC/FPC):
• Adding or relocating any water supply line
• Installing new showerhead rough-in (new studs, blocking, supply piping)
• Adding body spray system (new supply manifold)
• Replacing tankless water heater (new installation)
• Changing water heater fuel type (gas↔electric)
When no permit required:
• Like-for-like showerhead replacement (same location, same connection)
• Replacing handshower slide bar (no new piping)
• Water heater in-kind replacement (same fuel, same BTU ±10%)
Water Heater Code — FL Specifics
FPC Chapter 5 — Water Heaters:
• Tankless units require dedicated gas or electrical circuit
• Gas tankless: minimum 200,000 BTU installations need 1-inch gas supply in most FL applications
• Temperature relief valve required on all tankless units (ASME rated)
• FL Energy Code (FECC) requires EF ≥ 0.67 for gas storage; tankless typically EF 0.82–0.96
• South FL HVHZ: all outdoor tankless enclosures must meet Miami-Dade NOA 140 mph wind rating
• FL Statute 163.04 prohibits HOAs from preventing installation of solar water heaters
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fl master shower gpm calculation method: sum all simultaneous outlet GPM; body sprays each 0.5 GPM max per FPC 604.4.2; rain heads 1.5-2.5 GPM; handshower 1.5-2.5 GPM; tub filler 4.0 GPM; steam generator 0.1 GPM equivalent; total peak demand drives tankless BTU sizing
tankless water heater BTU formula: Required BTU/hr = GPM x 500 x ΔT x 8.33 / 60 where ΔT = desired output temp minus groundwater inlet temp; Florida groundwater: South 73F, Central 70F, North 67F, Panhandle 65F; at 120F output Central FL ΔT = 50F; 5 GPM x 500 x 50 x 8.33 / 60 = 173,542 BTU/hr needed
florida shower flow rate limits: FPC 604.4 - showerhead max 2.0 GPM at 80 psi; body spray max 0.5 GPM each; handshower max 2.0 GPM; bathtub filler max 4.0 GPM; when multiple heads on single valve aggregate must not exceed 2.0 GPM unless individual shutoffs installed per FPC 604.4 exception
fl water heater energy code FECC 2023: tankless gas EF minimum 0.82; electric resistance minimum 0.92; heat pump water heater EF 2.0+ preferred; fl statute 553.9085 requires efficient water heaters in new construction; SFWMD rule 40E-22 requires WaterSense labeled showerheads in new construction in SFWMD jurisdiction (Lee, Collier, Hendry, Glades, Palm Beach, Martin, St Lucie, Okeechobee, Broward, Miami-Dade, Monroe)
shower drain sizing per FPC table 709.1: 2 inch drain = 2.9 GPM max; 3 inch drain = 4.6 GPM max; 4 inch drain = 8.0 GPM max; recommend 3 inch for systems 3-6 GPM; 4 inch for systems 6+ GPM or with body spray panels
body spray compliance note: FPC allows unlimited body sprays if each outlet rated at 0.5 GPM or less AND each has individual shutoff; 16-spray panel = 8.0 GPM aggregate is code compliant; thermostatic valve required for systems with body sprays to prevent scalding
fl permit requirements master shower: mechanical permit required for new tankless water heater installation per FBC 105.2; plumbing permit for new rough-in piping per FPC 103; no permit for like-for-like showerhead replacement; HVHZ requires NOA-approved equipment for south florida installations