CA License #1037326|Bonded & insured|Office Mon–Fri 7:00 AM – 5:00 PM · Emergency line answered 24/7
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DASO PLUMBINGResidential & Commercial
Home/Service areas/San Francisco
Historic & Multi-Unit Plumbing • San Francisco, CA

San Francisco Historic & Multi-Unit Plumbing Solutions

Specialized plumbing engineered for San Francisco's multi-story Victorians, Edwardians, and commercial buildings. We replace aging cast iron vertical waste stacks, install mandatory seismic earthquake gas shutoff valves, and boost water pressure to upper floors.

Daso Plumbing work in San Francisco, CA
Commercial Overhead · San Francisco, CA
Overhead drainage & gas line routing
Licensed C-36
CA #1037326, active standing
Bonded & insured
Commercial and residential coverage
Written prices
Fixed scope and price before work starts
Photo-documented
Every diagnostic and repair logged
San Francisco · local conditions

Plumbing Engineered for San Francisco's Multi-Story Flats & Chases

San Francisco's architectural heritage—from ornate Victorian row houses in the Mission and Pacific Heights to Marina flats and multi-family brownstones—presents complex plumbing conditions rarely found in suburban homes.

Zero-lot-line structures feature vertical cast iron waste and vent stacks installed 80 to 120 years ago that are now rotting and leaking into lower tenant ceilings. Furthermore, hilly topography often leaves top-floor flats with sluggish shower pressure, while City ordinances mandate seismic earthquake gas shutoff valves . Daso Plumbing brings master-level craftsmanship to San Francisco properties.

Top Drain Failure
Rusted Cast Iron Vertical Stacks
Seismic Safety
Mandatory Earthquake Gas Valves
Upper Floor Pressure
Variable-Speed Booster Pumps
Commercial Dining
Backflow & Boiler Manifolds

All services →

What goes wrong here

Common Plumbing Failures in San Francisco Buildings

Multi-story stack leaks, low hilltop pressure, and earthquake vulnerabilities.

Cast Iron Stack Cracks

Century-old vertical drain stacks develop hairline longitudinal cracks, allowing sewage dampness and sewer gas odors to seep into wall cavities.

Seismic Gas Ruptures

During earthquake tremors, building movement can fracture rigid gas risers, creating catastrophic fire hazards without an automatic shutoff valve.

Hilltop Weak Pressure

Third- and fourth-floor flats in hill neighborhoods experience weak dribbling showers during peak morning hours without a booster pump.

Zero-Lot Chases

Shared property line walls and narrow lightwells make plumbing access difficult, requiring specialized vertical pipe replacement expertise.

Our work

Work we've done in San Francisco.

Real systems installed by Daso crews on Peninsula properties.

Overhead Utility & Drainage Piping — San Francisco, CA
San Francisco, CA
Overhead Utility & Drainage Piping
Daso crew fitting overhead drainage and seismic gas runs.
Commercial Backflow Station — San Francisco, CA
San Francisco, CA
Commercial Backflow Station
Dual backflow preventer assembly and underground transition.
Commercial DWV Stack Framing — San Francisco, CA
San Francisco, CA
Commercial DWV Stack Framing
Multi-story cast-iron waste piping in commercial steel studs.
Specialised for San Francisco

What we're usually called in for here.

01

Cast Iron Stack Replacement

Surgically replace rotting vertical cast iron sewer, waste, and vent stacks in multi-story flats using noise-dampened cast iron or heavy-gauge ABS without displacing tenants.

  • Vertical chase access expertise
  • Acoustic quiet-pipe dampening
  • Eliminates sewer gas odors
02

Seismic Gas Shutoff Valves

Full compliance with City of San Francisco Building Code Chapter 12A. Certified installation of automatic motion-sensitive earthquake gas shutoff valves on commercial and residential meters.

  • City of SF permit sign-off
  • Tested to CSA / ANSI standards
  • Manual reset bypass provided
03

Water Pressure Booster Pumps

Restore robust, invigorating water pressure to top-floor flats. We install smart variable-frequency drive (VFD) booster pumps that automatically adjust power to match demand.

  • Constant 60 PSI to all floors
  • Whisper-quiet acoustic mounting
  • Compact mechanical closet footprint
FAQ

San Francisco plumbing questions

What are the San Francisco requirements for seismic gas shutoff valves?
Under San Francisco Building Code Chapter 12A, an approved seismic earthquake gas shutoff valve must be installed on any building undergoing a commercial alteration, change of occupancy, or residential remodel exceeding $50,000 in valuation. The valve automatically halts gas flow if significant seismic ground motion occurs, protecting dense urban wooden structures from catastrophic fires.
How do you replace rotting cast iron stacks in occupied Victorian flats?
Replacing vertical stacks in multi-family Victorians requires careful staging to minimize disruption. We open small, strategic inspection access portals in vertical plumbing chases, secure the upper pipe with heavy-duty riser clamps to prevent collapse, remove deteriorated sections, and install new no-hub cast iron or sound-insulated piping. Water service is typically restored at the end of each work day.
Why is shower water pressure so weak on upper-floor flats?
Every 10 feet of vertical elevation drop reduces water pressure by roughly 4.33 PSI. In a three-story flat built on a steep hill like Pacific Heights or Nob Hill, municipal supply pressure can drop to 30 PSI or lower by the time it reaches the top bathroom. Installing a compact, variable-speed booster pump in the basement mechanically pressurizes the line, ensuring a steady, luxurious 55–65 PSI at every showerhead.
Does Daso Plumbing handle restaurant backflow testing and kitchen boilers in SF?
Yes. We provide certified annual backflow prevention assembly testing and reports directly to the San Francisco Public Utilities Commission (SFPUC). We also install commercial high-flow water softeners, grease trap connections, and multi-unit commercial boiler arrays across the city.
Next step

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