South Side Maui Water Report
Covering Kīhei, Māʻalaea, Wailea, and Mākena. Compiled from EWG's Tap Water Database and the County of Maui Department of Water Supply. Your exact numbers can vary by address — book a consult and we'll confirm your specific system.
Where your water comes from
South Side's water comes from the same Central Maui system that serves Wailuku, Kahului, and the rest of Town — drawn from the Iao Aquifer beneath the West Maui Mountains, naturally filtered through volcanic rock, then disinfected. But your water doesn't stop there: it travels considerably further to reach Kīhei, Māʻalaea, Wailea, and Mākena, through miles of additional distribution piping — some of it decades old.
Same source, longer journey
Because South Side shares its source with Town, the contaminant profile below reflects the same underlying testing data — including arsenic at a level uncommon among Hawaiʻi utilities. But water quality isn't just about the source; it's also about everything the water passes through on the way to your tap. The longer the distribution network, the more opportunity for the water to pick up additional sediment, corrosion byproducts, and aging-infrastructure effects that wouldn't necessarily show up in source-level testing.
Arsenic
Arsenic
Cancer riskWhat is this and where does it come from?
Arsenic is a potent carcinogen and one of the most common serious contaminants in U.S. drinking water. It can occur naturally in groundwater or enter from agricultural and industrial sources. This system is one of the relatively few in Hawaiʻi with a consistent, detectable arsenic presence.
Disinfection Byproducts
Total Trihalomethanes (TTHMs)
Cancer riskWhat is this and where does it come from?
Forms when chlorine reacts with naturally occurring organic matter — a byproduct of disinfection, not outside contamination.
Haloacetic Acids (HAA5)
Cancer riskWhat is this and where does it come from?
A group of five chemicals formed during disinfection. Linked to cancer risk and potential harm during pregnancy.
Bromoform
Cancer riskWhat is this and where does it come from?
One of four trihalomethanes formed during chlorine disinfection.
Dibromochloromethane
Cancer riskWhat is this and where does it come from?
One of four trihalomethanes formed during disinfection.
Dibromoacetic Acid
Cancer riskWhat is this and where does it come from?
A haloacetic acid formed during disinfection.
Bromochloroacetic Acid
Cancer riskWhat is this and where does it come from?
A haloacetic acid formed during disinfection.
Bromodichloromethane
Cancer riskWhat is this and where does it come from?
One of four trihalomethanes formed during disinfection. Linked to cancer risk and possible harm to fetal growth.
Trichloroacetic Acid
Cancer riskWhat is this and where does it come from?
A haloacetic acid formed during disinfection.
Chloroform
Cancer riskWhat is this and where does it come from?
The most common trihalomethane, formed during chlorine disinfection.
Dichloroacetic Acid
Cancer riskWhat is this and where does it come from?
A haloacetic acid formed during disinfection.
Agricultural & Industrial Legacy
Hexavalent Chromium
Cancer riskWhat is this and where does it come from?
A carcinogen that can come from industrial pollution or occur naturally in mineral deposits and groundwater.
Nitrate
Cancer & infant health riskWhat is this and where does it come from?
Enters water from fertilizer runoff, septic systems, and urban runoff. Can cause oxygen deprivation in infants and increases cancer risk.
Endocrine Disruptor
Chlorate
Thyroid functionWhat is this and where does it come from?
Forms as a byproduct of disinfection. Impairs thyroid function, making exposure most concerning during pregnancy and childhood.
What this means for you
Your water meets every federal and state legal limit. But "legal" reflects standards that haven't been updated in nearly 20 years, not the latest independent health science. Several disinfection byproducts here are found at many times the health guideline set by EWG's scientists, and arsenic — while under the legal limit — shows up consistently at a level far above what's considered optimal. And because South Side sits at the end of a long distribution run from the Central system, your water has more distance and more aging pipe to travel through than Town's before it reaches your tap — meaning it's reasonable to expect your water carries this same profile, plus whatever it picks up along the way.
What's in your pipes matters too. These results describe the water as it leaves the utility's system. On the way to your tap it can pick up lead, copper, or other metals from older city plumbing or from the pipes, fixtures, and solder in your own home. A utility's results can't see that, but testing your tap can.
No fluoride added
Maui DWS has never added fluoride to this system — only trace natural fluoride is present (0.0458 ppm), well below the level found in many mainland systems.
Book Your Free Consult
We'll confirm which utility serves your address, walk through what your results mean, and recommend the right filtration for your home — no pressure, just answers.
Book a Free Consult