Is San Dimas Tap Water Safe to Drink?

Can You Drink Tap Water in San Dimas?

Yes, San Dimas's tap water is generally considered safe to drink as San Dimas has no active health based violations of the Safe Drinking Water Act (SDWA) that we are aware of. Other factors such as lead piping in a home, or low levels of pollutants on immunocompromised individuals, should also be considered, however. To find more recent info we might have, you can check out our boil water notice page or the city's water provider website.

According the EPA’s ECHO database, from April 30, 2019 to June 30, 2022, San Dimas's water utility, Gswc-San Dimas, had 0 violations of the Safe Drinking Water Act. For more details on the violations, please see our violation history section below. This assessment is based on the Gswc-San Dimas water system, other water systems in the city may have different results.

While tap water that meets the EPA health guidelines generally won’t make you sick to your stomach, it can still contain regulated and unregulated contaminants present in trace amounts that could potentially cause health issues over the long-run. These trace contaminants may also impact immunocompromised and vulnerable individuals.

The EPA is reviewing if it’s current regulations around pollutant levels in tap water are strict enough, and the health dangers posed by unregulated pollutants, like PFAS.

San Dimas Tap Water Safe Drinking Water Act Violation History - Prior 10 Years

Below is a ten year history of violations for the water system named Gswc-San Dimas for San Dimas in California. For more details please see the "What do these Violations Mean?" section below.

Is there Lead in San Dimas Water?

Based on the EPA’s ECHO Database, 90% of the samples taken from the San Dimas water system, Gswc-San Dimas, between sample start date and sample end date, were at or below, 0.0027 mg/L of lead in San Dimas water. This is 18.0% of the 0.015 mg/L action level. This means 10% of the samples taken from San Dimas contained more lead.

While San Dimas water testing may have found 0.0027 mg/L of lead in its water, that does not mean your water source has the same amount. The amount of lead in water in a city can vary greatly from neighborhood to neighborhood, or even building to building. Many buildings, particularly older ones, have lead pipes or service lines which can be a source of contamination. To find out if your home has lead, we recommend getting you water tested.

No amount of lead in water is healthy, only less dangerous. As lead accumulates in our bodies over time, even exposure to relatively small amounts can have negative health effects. For more information, please check out our Lead FAQ page.

Are there PFAS in San Dimas Tap Water?

Currently, testing tap water for PFAS isn’t mandated on a national level. We do have a list of military bases where there have been suspected or confirmed leaks. There appears to be at least one military base - AZUSA CA NCCOSC MORRIS DA - near San Dimas with suspected leaks.

With many potential sources of PFAS in tap water across the US, the best information we currently have about which cities have PFAS in their water is this ewg map, which you can check to see if San Dimas has been evaluated for yet.

Our stance is better safe than sorry, and that it makes sense to try to purify the tap water just in case.

What do these Violations Mean?

Safe Drinking Water Act Violations categories split into two groups, health based, and non-health based. Generally, health based violations are more serious, though non-health based violations can also be cause for concern.

Health Based Violations

1. Maximum contaminant levels (MCLs) - maximum allowed contaminant level was exceeded.
2. Maximum residual disinfectant levels (MRDLs) - maximum allowed disinfectant level was exceeded.
3. Other violations (Other) - the exact required process to reduce the amounts of contaminants in drinking water was not followed.

Non-Health Based Violations

1. Monitoring and reporting violations (MR, MON) - failure to conduct the required regular monitoring of drinking water quality, and/or to submit monitoring results on time.
2. Public notice violations (Other) - failure to immediately alert consumers if there is a serious problem with their drinking water that may pose a risk to public health.
3. Other violations (Other) - miscellaneous violations, such as failure to issue annual consumer confidence reports or maintain required records.

SDWA Table Key

For more clarification please visit the EPA's data dictionary.