Friends of the planet, look away now: a 100-tonne pile of rubbish, including broken bottles and hypodermic needles, has washed up on Chongming Island in Shanghai, China.

Household rubbish, plastic bags, and clothing were visible in photos and videos posted to social media, with waste littering beaches and in some places covering the water completely.

The stomach-churning sight is believed to be the fault of two ships illegally dumping trash at the mouth of the Yangtze River, although the Chinese government hasn't yet named the culprits publicly.

Worryingly for locals, much of the rubbish has built up around Dongfengxisha Reservoir on the island, one of the four main sources of drinking water for Shanghai.

The better news is that official tests show the reservoir hasn't been polluted and the water is still safe to drink, and a team of 40 workers is currently busy trying to clean up the mess.

"Much garbage has been floating into reed marshes near the reservoir, which had increased the difficulty of clearing them," the deputy general manager of the island's water source management company Song Jian told Yang Jian at Shanghai Daily.

More than 17,000 packs of rubbish have reportedly been collected in the last week alone, and the clean-up operation is expected to take another two weeks.

Fortunately the garbage hasn't drifted as far as the Qingcaosha Reservoir further downstream, which is the area's main reservoir for drinking water, but local wildlife have been caught up in the trash dump.

The disturbing sight of floating trash is another reminder that all our rubbish has to go somewhere – which is why cutting down on waste and recycling our goods is such an important part of keeping the planet healthy.

And when we do need to take our trash out somewhere, we need to do it responsibly: dumping all our rubbish in the oceans harms marine life and human beings alike.

With the unnamed suspects now in custody for the dumping near Chongming Island we'd like to think this is the last of these irresponsible acts we're going to hear about – ultimately we're hurting ourselves most of all.

As the Guardian's Benjamin Haas reports, a commenter on Chinese social media put it like this: "This is so sad, just humanity digging its own grave."