BEIJING — A couple in China were horrified to discover that they had been drinking toilet water for six months due to a plumbing error at their new apartment.

A man, identified only as Mr Tan, and his girlfriend were perplexed when they began developing health issues shortly after moving into a rental apartment in Beijing in May this year. 

Mr Tan reportedly started losing hair and developing acne, while his partner suffered from a cough and discomfort in her chest.

About half a year after moving in, Mr Tan realised that he had not paid a single water bill in addition to the monthly 10,000 yuan (S$1,900) rent, and yet the apartment’s water supply had surprisingly not been disconnected.

Suspicious, he decided to run some tests with their water meters in November.

He was puzzled to discover that the tap water meter’s reading did not increase when he ran the faucets. However, the number on the grey or reclaimed water meter (中水 in Chinese) unmistakably rose instead.

The couple claimed that they first requested help from housekeeping crew from Ziroom, a home rental platform in China that leased the unit. However, the crew reportedly found no issues.

The pair then enlisted the services of maintenance personnel on Nov 22, who upon investigation uncovered an extra pipe that linked the toilet and tap water pipes.

Consequently, this resulted in the mixing of tap water with reclaimed water from the toilet pipe in Mr Tan’s apartment, Chinese media reported.

Grey or reclaimed water is household waste water that can be reused for some purposes without purification, Collins Dictionary states. These include toilet flushing, gardening and car washing.

However, the water is not suitable for drinking or showering, and should not be used for washing food items or cooking — all things that Mr Tan and his girlfriend had been doing for the last six months.

Following the stomach-churning discovery, the couple is reportedly seeking monetary damages from Ziroom.

Jiupai News quoted Mr Tan's girlfriend as saying: “When (we) first rented (the apartment), you didn’t inform me (of this). I kept using the reclaimed water. If I had not been unwell, I would never have discovered this.”

In response, the rental firm claimed that tenants had the option to use either drinking water or water sourced from a nearby well by adjusting valves. However, the couple claimed that they were never informed of this.

Ziroom also asserted that the well water had passed quality tests in March, but was suitable only for tasks such as flushing toilets and watering plants.

The issue has become a hot topic in China, with related hashtags amassing more than six million views on microblogging site Weibo.

Many social media users were alarmed that the piping error had gone undetected for so long.

One Weibo user wrote: ​​“This so-called reclaimed water doesn’t have any odour or off-looking colour? (They just) kept using it, kept drinking it?”

Another commented: “How to distinguish what kind of water it is? Suddenly (I’m) really worried.”

While some people criticised Ziroom and called on the company to take responsibility, others opined that the fault lies with the utilities provider instead.

A user said: “I feel like it doesn’t have much to do with Ziroom. You have to ask the water company.”

A handful of online users, however, have accused Mr Tan and his girlfriend of overreacting.

One person remarked: “Well water that has passed the water quality test should be fine. Can having acne really be considered abnormal?”

Another said: “Beijing city has no real reclaimed water. In order to pass inspection, they all connect tap water and reclaimed water pipes. For drinking water and cooking, I use reverse osmosis filtered or bottled water.”

A startup founded in 2011 and backed by Japanese firm Softbank, Ziroom is now one of the leading players in China’s long-term rental market.

Negotiations for compensation between the couple and Ziroom are reportedly still ongoing. ADDITIONAL REPORTING BY RUTH YEO