Mae Sai residents warned against using local water after tests reveal high arsenic and heavy metal levels

Expats and residents living in Mae Sai need to immediately stop using local tap or untreated water for consumption. Recent tests have revealed dangerous levels of arsenic and heavy metals in the water supply across five sub-districts.

According to a report by Thansettakij (in Thai), authorities have issued a strict warning against the direct use of local water in these affected areas. The tests showed contamination exceeding established safety standards, prompting the immediate health advisory.

What this means for you

If you live in or are currently visiting Mae Sai, you should take immediate precautions regarding your water usage. Heavy metals like arsenic cannot be boiled away, and standard carbon water filters are often insufficient to remove them.

To protect your health, take the following steps:

• Switch to bottled water: Use bottled water exclusively for drinking, cooking, making ice, and brushing your teeth.
• Verify your filtration: If you rely on a home filtration system, check if it uses reverse osmosis (RO), which is generally required to filter out heavy metals. Standard jug filters will not protect you.
• Check your area: Contact your landlord, juristic person, or local municipal office to confirm if your specific sub-district is among the five under the advisory.

While the report does not specify the exact source of the contamination, heavy metal runoff can occasionally affect local water tables in northern Thailand. Rely on bottled water until local authorities officially declare the tap water safe for use again.