Spools in Arizona — The Small-Pool-Spa Combo That Fits Yards Pools Can't

What a spool actually is

A spool — sometimes called a cocktail pool, plunge pool, or spa-pool — is a small pool sized between a true spa and a full swimming pool. Typical footprint: 10–16 ft long, 6–10 ft wide, 4–5 ft deep, with bench seating, jets, and a heater. It's deep enough to cool off and float in, big enough for 4–8 adults to lounge, and small enough to heat to spa temperature when you want hot-tub use.

Originally a coastal-builder solution for tight urban lots, the spool has become one of the fastest-growing water-feature categories in metro Phoenix — driven by smaller new-build lots, casita-yards, downtown infill, and HOAs that cap pool size.

Investment range in Phoenix

Most spools land between $55,000 and $110,000 installed in the Valley. Drivers: shell construction (gunite vs precast vs fiberglass), heating system (gas vs heat pump vs both), jet count, automation, and deck materials. A fully built gunite spool with travertine deck, gas heater, automation, and LED lighting typically lands around $75K–$95K — meaningfully less than a full pool, more than a standalone spa.

Operating cost is closer to a spa than a pool: smaller water volume means cheaper to heat, less evaporation, lower chemical load, smaller pump. Expect $90–$180/month in summer and $120–$220/month in winter if you heat it spa-style.

Who a spool is for

Spools earn their cost in five specific scenarios: (1) lots under 5,000 sq ft where a full pool eats the entire yard, (2) HOAs or zoning that cap pool size or setback, (3) couples and empty nesters who want water but won't host pool parties, (4) clients who want year-round hot-tub use AND summer cool-off in one feature, and (5) anyone who wants a strong visual water feature without committing to pool-scale water and energy bills.

Spools are less ideal for families who want kids swimming laps, for serious lap swimmers, or for households that genuinely host poolside parties — the footprint is wrong for any of those.

Spool vs spa vs full pool

• Spa: 6–8 ft, 3 ft deep, holds 4–6 adults, runs 100–104°F year-round, $25K–$60K installed. Hot only — no cool soak, no float.
• Spool: 10–16 ft, 4–5 ft deep, holds 4–8 adults, runs 78–104°F depending on mode, $55K–$110K installed. Hot soak in winter, cool plunge in summer.
• Full pool: 28–40+ ft, 3.5–8 ft deep, holds 10+ swimmers, $90K–$200K+ installed. Lap swim, kid swim, party scale.
• The middle slot is real — a spool isn't a compromise on the other two, it's its own category for households whose actual life fits between them.

Heating — gas, heat pump, or both

Gas heater: fast (raises temp 30–40°F in a few hours), expensive to run for daily use, perfect for occasional spa-temp soaks. Required for fastest reheats.

Heat pump: 3–5x more efficient than gas for maintaining temperature, slower to heat (24+ hrs from cold), perfect for keeping the spool at a steady 88°F all summer or 102°F all winter.

Best of both: a dual system — heat pump maintains baseline, gas boosts on demand. Adds $4K–$7K but pays back in 2–4 years if you actually use the spool year-round.

Sizing for your lot

• Standard rectangular spool: 10x14 ft, 4 ft deep. Fits most courtyards and side yards.
• Larger 'social spool': 14x16 ft, 4.5 ft deep, bench seating along two walls. Better for groups of 6–8.
• Linear plunge spool: 8x18 ft, 4 ft deep, narrow footprint that doubles as a modern water feature visible from inside the house.
• ARS §36-1681 barrier law applies — every spool requires a 5-ft fence with self-closing/self-latching gate, same as a pool.

FAQs — spools

Real questions we get from clients considering a spool.

• Can a spool be used as a hot tub? Yes — flip the heater to spa mode, raise to 100–104°F, jets on. Most clients use this mode 6 months a year.
• Can kids swim in a spool? They can play, splash, and learn basic water comfort, but it's too short for actual lap swim. Great learning environment under supervision.
• Are spools safe for pets? Same rules as a pool — fence, supervision, doggy ramp if a senior dog uses it. The smaller footprint actually makes pet rescue easier.
• Does a spool count as a pool for HOA rules? Usually yes — most HOAs and cities classify by depth (over 24 inches = pool), not by size. Verify with your specific CC&Rs.
• How long to build? 6–10 weeks for a gunite spool, vs 10–16 weeks for a full pool.
• Resale impact? Generally treated as a pool by appraisers — slight discount to a full pool in family-home submarkets, often parity or premium in luxury condo/casita submarkets where lot size makes a full pool impossible.
• Can I add a spool to an existing yard? Yes — same construction sequence as a small pool. Tight-access excavation may add cost on backyard-only sites.
• Can a spool integrate with a splash pad or bubblers? Yes — bubblers in the bench seat or a small splash zone next to the spool are common and add minimal cost during construction.