DC Water Filter

A Val Town email trigger that filters DC Water emergency alerts by proximity to your home address. Only alerts within a configurable radius in the NE quadrant are forwarded to your inbox.

1. DC Water sends emergency alert emails (outages, water main repairs, etc.)
2. You forward these to your Val Town email trigger address
3. The val extracts the location from the email body
4. Locations outside the NE quadrant are dropped
5. Remaining locations are geocoded via the US Census Bureau API
6. If the location is within your configured radius, the email is forwarded to you

The filter is intentionally fail-open: if location parsing or geocoding fails, the email is forwarded with a note about what went wrong. The only hard filter is the NE quadrant check.

backend/
  index.ts              # Val Town email trigger entry point
shared/
  parsing.ts            # Location extraction, parsing, geocoding, distance calc
  parsing_test.ts       # Deno tests
examples/
  *.eml                 # Sample DC Water alert emails for testing

Set these in your Val Town environment:

The proximity radius is set to 1.0 miles in backend/index.ts.

deno test shared/parsing_test.ts --allow-read --allow-net --no-config

--no-config is needed to avoid deno.json pulling in Val Town types that aren't available locally.

• Geocoding: US Census Bureau geocoder (free, no API key, handles DC intersections well)
• LLM fallback: When deterministic parsing can't produce a geocodable address, OpenAI gpt-4o-mini rewrites the location string before a second geocode attempt
• Email parsing: Location is extracted from the pattern located on/in [LOCATION]. Some customers found in DC Water alert templates