Swimming pool rules in Hillsborough, California
Yes, with a building permit. Pools, spas and hot tubs normally must be 20 feet from side and rear lot lines and 25 feet from the street, but can be as close as 5 feet to a side or rear line if they're 40 feet from the neighbor's house and the neighbor agrees in writing. A safety barrier and at least two state drowning-prevention features are required.
| Interior (side/rear) setback | 20 ft [2] |
| Street setback | 25 ft [3] |
| Reduced setback with neighbor consent | 5 ft from lot line, 40 ft from neighbor's house [5] |
| Measured from | Edge of coping (or water) [8] |
| Barrier | Required for pools/spas built after 9-7-1993 [9] |
| Drowning-prevention features | At least 2 of 7 [10] |
| Soils report | If within 7 ft of a descending slope [11] |
| Equipment enclosure in setback | Max 6 ft high / 40 sq ft [12] |
Permits
A new or remodeled pool or spa needs a building permit from the Building Department. Submittals need a site plan showing the pool and equipment with distances to property lines, structural drawings and calculations, and a project valuation; a pool within 7 feet of a descending slope needs a soils report [11].
Setbacks
The standard setback for pools, spas, hot tubs and pool equipment is 20 feet from interior (side/rear) lines [2] and 25 feet from any street line [3][1]. A pool, spa or hot tub may be placed in the interior setback [4] if it is at least 5 feet from the lot line [5], at least 40 feet from any neighboring house [6], more than 25 feet from any street line and no more than 8 feet high, and the adjoining neighbor states in writing that they don't object [7]. Setbacks are measured to the edge of the coping, or to the water's edge if there is no coping [8].
Pool equipment
Pool equipment in an enclosure may go in the setback if the enclosure is no more than 6 feet high and no more than 40 sq ft [12], at least 5 feet from property lines, 40 feet from neighboring houses and more than 25 feet from the street, and the neighbor signs off on the approved plans.
Barriers and safety
Every pool, hot tub or spa built after September 7, 1993 must have barriers to prevent unauthorized entry, subject to design review where applicable [9]. New or remodeled pools and spas must also have at least 2 of the 7 drowning-prevention measures in state law, such as an isolating enclosure, removable mesh fencing with a self-latching gate, an approved safety cover, door exit alarms or a pool alarm [10].
Lot coverage and hot tubs
Swimming pools count as hardscape toward the 50% cap on structural plus hardscape coverage [13]. Hot tubs and spas follow the same setback and barrier rules as pools [8][9].
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Next steps
- Get a survey and site plan showing the pool, coping and equipment with distances to property lines.
- If you want the pool or equipment within the 20-ft interior setback, get the adjoining neighbor's written no-objection and confirm the 40-ft distance to their house.
- Submit plans (3 full-size sets, structural details and calculations, valuation, soils report if near a slope) to the Building Division, (650) 375-7411.
- Choose at least two drowning-prevention features and show the barrier on the plans; fencing or barriers may also need design review with Planning ((650) 375-7422).
Common questions
- Do I need a permit for a pool in Hillsborough, California?
- Yes, a building permit is required. A safety barrier and at least 2 state drowning-prevention features are also required.
- How far must a pool be from the property line in Hillsborough, California?
- Pools, spas and hot tubs normally must be 20 feet from side and rear lot lines and 25 feet from the street.
- Can a pool be closer to the neighbor in Hillsborough, California?
- Yes. A pool can be as close as 5 feet to a side or rear line if it's 40 feet from the neighbor's house and the neighbor agrees in writing.
- Do I need a fence around a hot tub in Hillsborough, California?
- A barrier is required for pools and spas built after 9-7-1993. Fencing or barriers may also need design review with Planning.
California state rules for swimming pools
Pools need a city or county building permit, and local zoning sets setbacks. The state's Swimming Pool Safety Act (Health & Safety Code §115920 et seq.) adds safety rules:
- Drowning prevention features: when a building permit is issued for a new pool or spa, or to remodel one, at a private single-family home, it must have at least two of seven safety features (§115922):
- an enclosure that isolates the pool from the house
- removable mesh fencing (ASTM F2286) with a self-closing, self-latching gate
- a safety pool cover (ASTM F1346-23)
- exit alarms on doors and windows that open directly to the pool
- self-closing, self-latching devices on those doors, released at least 54 inches up
- a pool alarm (ASTM F2208; child-worn alarms don't count)
- other equally protective, independently verified means
- Some pairs don't count, such as a safety cover plus a pool alarm. The building official inspects before final approval.
- Enclosure standards (§115923): at least 60 inches high, no more than 2 inches of clearance at the bottom, gaps that won't pass a 4-inch sphere, no handholds or footholds, and gates that open away from the pool with self-latches at least 60 inches up.
- What counts as a pool: any structure with water over 18 inches deep, including above-ground pools, hot tubs and spas (§115921). Spas with a locking ASTM F1346 cover, apartment complexes and public pools are exempt (§115925).
- Small pools: the 2025 Residential Code exempts prefabricated pools under 24 inches deep from a building permit.
What the ordinance says
- Planning Requirements - Setback Requirements, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 2
The standard setback requirements for swimming pools, spas, hot tubs and pool equipment are:
- Planning Requirements - Setback Requirements, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 2
Twenty (20) feet from any interior property line; and,
- Planning Requirements - Setback Requirements, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 2
Twenty-five (25) feet from any street line property line.
- Sec. 17.24.010(B)(6), Municipal Code Title 17 Ch. 17.24 Required Setback Areas, p. 1
Unenclosed structures (such as tennis or other courts, play structures, arbors, swimming pools, spas, and hot tubs) if:
- Sec. 17.24.010(B)(6)(b), Municipal Code Title 17 Ch. 17.24 Required Setback Areas, p. 1
The structure is no closer than five feet from any lot line; and
- Sec. 17.24.010(B)(6)(c), Municipal Code Title 17 Ch. 17.24 Required Setback Areas, p. 1
The structure is at least forty feet from any adjoining residence; and
- Sec. 17.24.010(B)(6)(e), Municipal Code Title 17 Ch. 17.24 Required Setback Areas, p. 1
The adjoining affected property owner(s) (i.e., the owner(s) whose property is adjacent to the proposed structure) has indicated in writing that the affected owner has no objection to the proposed location.
- Sec. 17.24.030(B)(2), Municipal Code Title 17 Ch. 17.24 Required Setback Areas, p. 1
The edge of the coping, if any, of a swimming pool, spa, or hot tub shall be the measuring point. If there is no coping, the edge of the water in a swimming pool, spa, or hot tub shall be the measuring point.
- Sec. 15.56.010, Municipal Code Title 15 Ch. 15.56 Swimming Pool Safety Barriers, p. 1
Every swimming pool, hot tub, and/or spa (constructed after September 7, 1993) shall be protected by barriers to prevent unauthorized entry into the pool, hot tub and/or spa.
- Building Requirements, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 1
All submittals for new pools or spas, or the remodeling of existing pool or spa, the respective swimming pool or spa shall be equipped with at least 2 of the following 7 drowning prevention safety measures of Section 115922 of the CA Safety Code:
- Building Requirements, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 1
Pools located within 7 feet of a descending slope will require a soils report;
- Planning Requirements - Pool Equipment, General Requirements for New/Remodeled Pools and Spas (Building Department), p. 2
is not greater than 6 feet in height or 40 sq. ft. in size; and,
- Maximum Lot Coverage - Hardscape Coverage, Development Standards - Annotated Excerpts from the Zoning Ordinance (Revised July 2026), p. 11
This includes; driveways, uncovered parking spaces, roofed porches, swimming pools, tennis and play courts, uncovered patios and decks, walkways and steps, gazebos and pergolas, artificial turf*, and solar panels, etc.