A domestic helper in Hong Kong was arrested on Tuesday after being accused of putting urine into a glass of water that her employer later drank.
Police were called to the flat at Yau Hong House in Tin Shui Wai at 1.17am after receiving a report from the employer.
According to officers, the woman, 31, complained of feeling unwell after drinking the water and she later detected an odour from the glass.
"She called police after she suspected her domestic helper, 37, had poured urine into the glass of water," a spokesman for the force said.
The helper was arrested on suspicion of administering poison with an intent to injure.
Her employer was sent to Tin Shui Wai Hospital for treatment.
In Hong Kong, administering any poison or other destructive or noxious substances with an intent to injure carries a maximum penalty of three years' imprisonment under the Offences against the Person Ordinance.
A police source said the domestic helper was an Indonesian woman who had worked for the family of three - a local couple and their three-year-old son - since 2016.
She had recently been reprimanded by the couple over her performance, the source added.
An investigation showed the woman collected urine from the three-year-old boy at home and poured it into a bottle of water on Monday afternoon, according to the source.
Officers from Yuen Long criminal investigation unit are handling the case.
Dr Choi Kin, former president of the Hong Kong Medical Association, said drinking water mixed with urine was unlikely to cause an illness unless there were microbes transmissible in the urine that could be infectious through the oral route.
Current president Dr Ho Chung-ping said the issue was complicated, depending on the amount of urine drank and kidney function. He suggested the employer consult her own doctor.
In 2009, an Indonesian domestic helper was arrested for putting her menstrual blood into her employer's food. She was charged with one count of the offence, under the ordinance.
In that case, a forensic report had shown the food contained menstrual blood, but prosecutors eventually dropped the charge because they could not prove menstrual blood was a destructive or noxious substance.
This article was first published in South China Morning Post.