Tankless Water Heaters in San Jose, CA
On most tankless water heater installs, the gas supply, the venting and the condensate drain take more work than hanging the heater, and they are what the City inspects.
Signs you need this
What San José checks on an install
A tankless water heater needs a building permit in San José, and the City's tankless bulletin spells out what gets checked (City of San José Bulletin #290, dated 26 January 2023):
- Gas. Tankless units generally need much more gas than a storage tank, so the existing house piping has to be checked and resized if it falls short. That is often the bigger part of the job, and it is gas line work.
- Venting. Most units use positive pressure vents, usually stainless steel because the condensate is slightly acidic, and Type B vent is not acceptable for them. Vents have to end at least 4 feet from a property line.
- Size. The unit has to meet the first hour rating in the California Plumbing Code table. For a house with 2 to 2.5 bathrooms and 3 or 4 bedrooms, that is 67 gallons.
- Location. A gas unit cannot go in a bedroom, a bathroom, or a closet that opens into one unless it is listed for direct venting and approved for that use. Where an unnoticed leak could damage the structure, it needs a watertight pan with at least a 3/4 inch drain.
That is why two tankless quotes can land far apart. Ask any tankless quote you get whether it includes the gas sizing and the vent.
Ask any tankless quote you get whether it includes the gas sizing and the vent.
Tank or tankless
In a house with an undersized gas line or a long vent route, much of the cost of going tankless lands on the gas and the venting rather than the heater. Hard water matters too. San Jose Water puts its groundwater at 183 to 440 mg/L (San Jose Water), and that scale builds up in a tankless heat exchanger, so plan on descaling it on the manufacturer's schedule, or on a water softener.
If you are weighing a straight tank replacement instead, start with water heater repair and replacement.
How the job runs
- 1Size the unit to the house with the code's first hour rating
- 2Check the gas meter and piping for the full load, and resize if needed
- 3Permit first, then the unit, vent, condensate drain and power
- 4City inspection, then fire it up and set the temperature
Questions people ask
Does a tankless water heater need a permit in San Jose?
Yes, a building permit. The City's tankless bulletin covers what gets checked: the gas piping, the venting, the unit size and where it goes (City of San José Bulletin #290).
Why do tankless water heater quotes vary so much?
Tankless units generally need much more gas than a tank, so the house piping often has to be resized, and most use stainless steel vents. Ask any tankless quote you get whether it includes the gas sizing and the vent.
What size tankless water heater do I need?
The unit has to meet the first hour rating in the California Plumbing Code table. For a house with 2 to 2.5 bathrooms and 3 or 4 bedrooms, that is 67 gallons.
Do tankless water heaters need maintenance?
Yes, especially with hard water. San Jose Water puts its groundwater at 183 to 440 mg/L, and that scale builds up in the heat exchanger, so plan on descaling it on the manufacturer's schedule, or on a water softener.
Sources
- City of San José Bulletin #290, Tankless Water Heater Requirements (dated 26 January 2023) (checked October 2, 2026)
- San Jose Water, Hard and Soft Water FAQs (checked October 2, 2026)
Water where it should not be?
Call and describe what you are seeing. If it can wait until morning, we will say so.
Related work
Water Line Repair & Replacement
The service line from the meter to the house. Leaks, pressure problems and full replacements.
Slab Leak Detection & Repair
Found and located before anyone opens the floor. The finding is what saves you money, not the repair.
Whole Home Repiping
Galvanized or failing pipe replaced throughout the house, in copper or PEX.