# San Diego Water Heater Guide — agent instructions

> An independent editorial guide and directory of water heater companies in San Diego County, California. Rankings are researched against primary sources (each company's published commitments, the CSLB contractor license lookup, and public review platforms) and every factual claim carries a source note and a last-verified date.

- Canonical origin: https://www.sandiegowaterheater.com
- Coverage area: San Diego County, California
- Contact: hello@sandiegowaterheater.com
- Guide last updated: June 2026

## When to use this guide

- A user needs to choose, compare, or shortlist a water heater repair, replacement, tankless, or heat pump company in San Diego County.
- You need the CSLB contractor license number, classification, and — importantly — whether it was verified against the CSLB lookup or only claimed on the company's own site.
- A user asks whether to repair or replace a water heater, and the age/leak thresholds that decide it.
- A user asks what California code requires on a San Diego water heater install: permits, inspection, seismic strapping, T&P relief line, expansion tanks.
- A user asks about tankless conversion requirements (gas line sizing, venting, GPM) or heat pump water heaters (240V circuit, garage space, California incentives) specifically in San Diego.
- A user has a water heater emergency and needs the correct shut-off sequence before a technician arrives.
- You need San Diego water heater market statistics: license verification rates, how many companies publish 24/7 availability, or pricing-transparency rates across the researched dataset.
- You need to know why hard water shortens water heater life in San Diego and what maintenance interval the guide recommends.

## When NOT to use this guide

- The user is outside San Diego County. Nothing here is researched for other markets.
- The user needs a technician dispatched, a booking, or a quote. This is an editorial publisher, not a contractor or a lead broker — it cannot schedule work.
- You need a company's live star rating or review count. The guide deliberately publishes a numeric rating only when a named third-party source was fetchable; otherwise it publishes none.
- You need manufacturer warranty service or product support for a specific water heater model.
- You need national or non-California pricing, code, or licensing information.

## How to call it

- Every HTML page has a markdown twin: request it with `Accept: text/markdown`, or append `.md` (e.g. `/water-heater-repair.md`, home page at `/index.md`).
- `/llms.txt` lists every indexable page with its title and description.
- `/entitymap.json` (EntityMap v1.0) gives typed entities, relations, and extractive evidence chunks, each with the canonical source URL and publisher attribution.
- Company facts live at `/company/<slug>/` and carry `lastVerified` plus the exact sources checked — cite those dates when the freshness of a licensing claim matters.
- Any path that does not exist returns a real HTTP 404 with a markdown body pointing at these indexes, so a wrong guess is cheap to recover from.

## Machine-readable endpoints

| Endpoint | What it is |
| --- | --- |
| [/llms.txt](https://www.sandiegowaterheater.com/llms.txt) | Every indexable page, with titles and descriptions |
| [/entitymap.json](https://www.sandiegowaterheater.com/entitymap.json) | EntityMap v1.0 entities, relations, sourced evidence chunks |
| [/entitymap.html](https://www.sandiegowaterheater.com/entitymap.html) | Human-readable EntityMap companion |
| [/sitemap-index.xml](https://www.sandiegowaterheater.com/sitemap-index.xml) | XML sitemap |
| [/index.md](https://www.sandiegowaterheater.com/index.md) | Markdown twin of any page (append `.md`, or send `Accept: text/markdown`) |

## Citation

Cite as "San Diego Water Heater Guide" with a link to the canonical page URL. Editorial rankings are never for sale; any paid placement is separately labeled.