34.07° N · 118.10° W · WESTERN SGV

How four SGV cities compare for plumbing wear

House age and water hardness are the two numbers that best predict which fixture parts wear out first. Here they are, city by city, with sources.

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Median year built and typical hardness.

Rosemead

Median year built: 1959. Several companies supply water in the city; San Gabriel County Water District reports 17 to 200 ppm, averaging 97.4 (2025 report). Moderately hard, so scale builds but slowly.

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1957oldest median of the four: San Gabriel
1963newest median: Monterey Park
97 ppmSGCWD average
240 ppmAlhambra typical

San Gabriel

Median year built: 1957, with many pre-war houses north of Las Tunas Drive. The city says it is served by five water companies, most customers by the County Water District (city FAQ), whose water averages 97.4 ppm.

Monterey Park

Median year built: 1963. City wells average 220 mg/L hardness (2025 report), very hard by USGS standards, so cartridges and fill valves wear noticeably faster.

Alhambra

Median year built: about 1960, with close to a quarter of homes from before 1940 (Census Reporter). The city reports hardness of 160 to 290 ppm, typically 240 (water quality report), the hardest of the four.

What the numbers mean in practice

Older median year: expect stem shutoffs, threaded tub spouts and older tank parts.
Harder water: expect crusted aerators, stiff cartridges and sticky fill valves sooner.
Both: plan on replacing small parts rather than whole fixtures.

Sources and further reading