CHIANG RAI – People living near the Thai-Myanmar border in Mae Sai, Chiang Rai, are worried after more wells tested positive for arsenic. The affected wells are about 100 metres from the Sai River. Local families report that rashes and itching appear and last for weeks after using the water for bathing.
On May 29, Dr. Suebsakul Kitnugon from Mae Fah Luang University and Pienporn Deetes from International Rivers led a team to check water quality along the Thai-Myanmar border. They sampled water at Huafai, near the Tam Pha Chom community in Wiang Phang Kham, and at the first Thai-Myanmar Friendship Bridge.
This was a follow-up to a recent round of testing, which had already found high arsenic levels. Using a field testing kit, the team again found arsenic above safety standards, measuring 0.012 milligrams per litre.
For the first time, the team also tested six shallow wells used by locals within 100-150 metres of the river. Results showed arsenic levels between 0.06 and 0.11 milligrams per litre. The Pollution Control Department’s standard allows no more than 0.01 milligrams per litre.
Dr. Suebsakul said local authorities need to investigate further. At least 60 people in the community rely on these wells, mainly for bathing.
Boon Jaiwong, 57, a resident of Tam Pha Chom, said she developed rashes on her arms, legs, and neck after coming in contact with floodwater. The irritation lasted more than a week. She believes arsenic in the water caused her symptoms.
She now avoids using water from the river and hopes the problem is fixed soon.
Pienporn Deetes explained that both the Kok and Sai rivers have their sources in the Wa region of Shan State, Myanmar, where mining operations are common. Gold and rare earth mining near both rivers has been going on for several years.
Mining is believed to be the main source of the contamination. While it is harder to control pollution from activities across the border, she said, cooperation is possible if all sides work together.
On the same day, the team joined the local municipality to host a meeting about water pollution in the Sai, Ruak, and Mekong rivers. Community groups plan to gather on June 5, World Environment Day, at the Mae Fah Luang Bridge in Chiang Rai.
They will submit a petition to local and national leaders, including the Thai Prime Minister, Myanmar’s military government, the President of China, and Wa State military leaders. The petition asks for action to address mining-related pollution, which has made the water cloudy and unsafe as it passes through northern Thailand.
Arsenic in well water is a silent but serious threat, with long-term health risks including cancer, cardiovascular disease, and neurological damage. Regular testing, proper treatment, and awareness are critical for mitigating exposure, especially for private well users in high-risk areas.
If you rely on well water, consider testing through a certified lab and consulting local health authorities for guidance on safe water practices.
