Is Modesto, California Shower Water Safe? What's In Your Water (2026)
Khat Cruz
Last updated: April 2026.
Is Modesto, California Shower Water Safe?
Population: 218,464 · Water Source: Tuolumne River, Modesto Reservoir, Groundwater
Understanding what's in your shower water is crucial for your health and well-being, especially in Modesto, California. While Modesto's water meets regulatory standards, hidden contaminants and common issues like hard water can significantly impact skin, hair, and respiratory health. Don't let unknown factors affect your daily shower experience.
💧 Where Does Modesto's Water Come From?
Primary Source: Tuolumne River, Modesto Reservoir, Groundwater
Modesto's water supply is a blend of surface water from the Tuolumne River and Modesto Reservoir, supplemented by local groundwater wells. This multi-source system provides resilience but also means the water can carry characteristics from both surface and subterranean environments. The water undergoes conventional treatment processes to ensure safety.
Treatment: Coagulation, flocculation, sedimentation, filtration, and chloramination for disinfection.
🔬 What's In Modesto's Shower Water?
Here are the key contaminants detected in Modesto's water supply based on real testing data from the EWG Tap Water Database:
| Contaminant | Level Found | EPA Limit | EWG Guideline | Status |
|---|---|---|---|---|
| Perfluorohexane sulfonate (PFHXS) | 0.0000 ppt | 1e-05 ppt | 0.0000 ppt | ⚠️ Exceeds EWG Health Guideline (493x above) |
| Arsenic | 1.73 ppb | 10.0 ppb | 0.0040 ppb | ⚠️ Exceeds EWG Health Guideline (434x above) |
| Haloacetic acids (HAA5) | 36.20 ppb | 60.0 ppb | 0.100 ppb | ⚠️ Exceeds EWG Health Guideline (362x above) |
| Haloacetic acids (HAA9) | 20.08 ppb | No federal limit | 0.060 ppb | ⚠️ Exceeds EWG Health Guideline (335x above) |
| Total trihalomethanes (TTHMs) | 44.80 ppb | 80.0 ppb | 0.150 ppb | ⚠️ Exceeds EWG Health Guideline (299x above) |
| Trichloroacetic acid | 13.46 ppb | No federal limit | 0.100 ppb | ⚠️ Exceeds EWG Health Guideline (135x above) |
| Chromium (hexavalent) | 2.58 ppb | No federal limit | 0.020 ppb | ⚠️ Exceeds EWG Health Guideline (129x above) |
| Chloroform | 41.04 ppb | No federal limit | 0.400 ppb | ⚠️ Exceeds EWG Health Guideline (103x above) |
| Dichloroacetic acid | 14.34 ppb | No federal limit | 0.200 ppb | ⚠️ Exceeds EWG Health Guideline (72x above) |
| Bromodichloromethane | 2.33 ppb | No federal limit | 0.060 ppb | ⚠️ Exceeds EWG Health Guideline (39x above) |
Contaminant Details
Perfluorohexane sulfonate (PFHXS)
The health guideline of 0.001 ppt for perfluorohexane sulfonate was defined by EWG based on studies by Phillipe Grandjean of Harvard University and many other independent researchers who found reduced effectiveness of vaccines and adverse impacts on mammary gland development from exposure to PFOA and PFOS, the two PFAS most widely detected in drinking water. This health guideline harm to the developing immune system.
Comparison: State average: 0.0000 ppt. National average: 0.0000 ppt.
Shower Impact: Contaminants in shower water can be absorbed through the skin and inhaled as steam, increasing your daily exposure beyond what you get from drinking water alone.
Arsenic
The health guideline of 0.004 ppb for arsenic was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.
Comparison: State average: 0.899 ppb. National average: 0.624 ppb.
Shower Impact: Arsenic in shower water can be absorbed through the skin. Long hot showers increase exposure time and absorption.
Haloacetic acids (HAA5)
The health guideline of 0.1 ppb for haloacetic acids (HAA5) was defined by as . This health guideline protects against cancer.
Comparison: State average: 35.45 ppb. National average: 19.82 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Haloacetic acids (HAA9)
The health guideline of 0.06 ppb for haloacetic acids (HAA9) was defined by EWG . This health guideline protects against cancer.
Comparison: State average: 15.50 ppb. National average: 23.70 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Total trihalomethanes (TTHMs)
The health guideline of 0.15 ppb for trihalomethanes was defined by in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level. as a draft public health goal, the level of drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.
Comparison: State average: 27.09 ppb. National average: 29.06 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Trichloroacetic acid
The health guideline of 0.1 ppb for trichloroacetic acid was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
Comparison: State average: 3.71 ppb. National average: 6.57 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Chromium (hexavalent)
The health guideline of 0.02 ppb for chromium (hexavalent) was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.
Comparison: State average: 0.812 ppb. National average: 0.440 ppb.
Shower Impact: Hexavalent chromium can be absorbed through the skin during bathing, adding to overall exposure beyond drinking water.
Chloroform
The health guideline of 0.4 ppb for chloroform was defined by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
Comparison: State average: 10.45 ppb. National average: 16.20 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Dichloroacetic acid
The health guideline of 0.2 ppb for dichloroacetic acid was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
Comparison: State average: 4.69 ppb. National average: 8.00 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
Bromodichloromethane
The health guideline of 0.06 ppb for bromodichloromethane was defined by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
Comparison: State average: 5.64 ppb. National average: 5.89 ppb.
Shower Impact: These disinfection byproducts become airborne in hot shower steam. You can inhale and absorb them through your skin, potentially increasing your exposure beyond just drinking water.
🧴 How Modesto's Water Affects Your Skin, Hair & Health
When you shower, contaminants in the water don't just wash off — they're absorbed through your skin and inhaled as steam. Here's how Modesto's water quality may be affecting you:
🧖 Skin Effects
- Increased dryness and flakiness due to chloramines and hard water.
- Exacerbation of eczema and other skin sensitivities from irritants.
- Soap scum residue, preventing thorough rinsing and leaving a film.
- Potential for skin irritation or rashes from disinfection byproducts.
💇 Hair Effects
- Dullness and lack of shine from mineral buildup (hard water).
- Dryness, frizz, and brittleness caused by chlorine/chloramines.
- Faster fading of dyed hair color due to harsh chemicals.
- Reduced lathering of shampoos and conditioners, leading to less effective cleaning.
🫁 Respiratory Effects
- Inhalation of chloramines and disinfection byproducts (TTHMs, HAA5s) in shower steam.
- Potential for respiratory irritation, especially for individuals with asthma or allergies.
- Increased risk of asthma attacks or breathing difficulties from chemical vapors.
- General discomfort from strong chemical odors during hot showers.
✅ What You Can Do About It
Test Your Water
Get a home water test kit or professional analysis to understand the specific contaminants and hardness levels in your Modesto home's water.
Install a Quality Shower Filter
A good shower filter can significantly reduce chlorine, chloramines, heavy metals, and some disinfection byproducts, improving skin and hair health.
Limit Shower Time and Ensure Ventilation
Shorter showers reduce exposure time to chemical vapors, and proper ventilation minimizes the concentration of airborne contaminants in your bathroom.
Moisturize Immediately After Showering
Applying a moisturizer to damp skin helps lock in hydration, counteracting the drying effects of hard water and chlorine.
Consider a Water Softener for Hardness
If hard water is a major concern, a water softener can remove mineral ions, preventing buildup and improving the feel of your skin and hair.
Protect Your Skin & Hair From Modesto's Water
The easiest way to remove chlorine, heavy metals, and other contaminants from your shower water.
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Related Reading
- psoriasis triggered by shower water
- trihalomethanes in treated water
- hexavalent chromium in water
- shower water quality in Anaheim, California
- shower water quality in Bakersfield, California
Is Modesto tap water safe to shower in?
Yes, Modesto's tap water meets all federal and state safety standards for showering. However, even compliant levels of disinfectants and minerals can cause issues like dry skin, hair damage, and respiratory irritation for sensitive individuals or those seeking optimal water quality.
Why does my skin feel dry after showering in Modesto?
Modesto's water is moderately hard, meaning it contains higher levels of minerals like calcium and magnesium. These minerals, along with chloramines used for disinfection, can strip natural oils from your skin, leading to dryness, irritation, and even exacerbating conditions like eczema.
Will a shower filter help with the chlorine smell in Modesto water?
Absolutely. Shower filters are highly effective at reducing chlorine and chloramines, which are primarily responsible for the chemical smell in your shower water. By removing these disinfectants, a filter can significantly improve the smell and overall showering experience.
How does Modesto's hard water affect my hair?
Hard water in Modesto can leave mineral deposits on your hair, making it feel dull, brittle, and difficult to manage. It can also prevent shampoos from lathering effectively, leading to less thorough cleansing and potentially causing hair color to fade faster.
Are there any specific concerns for children showering in Modesto?
Children's skin is more permeable and they may be more sensitive to irritants like chloramines and hard water minerals, potentially leading to increased dryness or skin rashes. Inhaling disinfection byproducts in shower steam is also a consideration for long-term health, making filtered water beneficial.
