Businessmen from the Chinese city of Harbin are planning to sue the state-owned chemical company blamed for poisoning the water supply.
Businessmen say the river will remain polluted
Water to the city was cut off last month after an explosion at the plant allowed 100 tonnes of benzene to spill into the Songhua river.
The businessmen's lawyer told the BBC pollution would be a long-term problem.
Hu Fengbin said the group wanted the firm to clean the river and to compensate them for loss of business.
"This pollution will not go away with the flow of the water because the chemical will be deposited on the river bed," Mr Hu told the BBC.
"The chemical won't disappear for several years. The chemical won't easily be broken down so the damage will be long-term.
"The compensation is not the most important thing. The most important thing is that from now on the water we drink is clean water. Whatever you provide - money or other resources - you must make the water clean."
The 20 business owners have filed a lawsuit against the firm, which is based up river in Jilin, where the explosion took place.
Correspondents say it is thought to be the first legal action following the spill and is unusual for China, where individuals rarely sue state-owned institutions.
There was no indication as to whether the court will allow the case to be heard.
Mr Hu said if the suit is rejected in Jilin, they will take their case to the supreme court in Beijing.
It was more than two weeks after the 13 November explosion that Harbin's water was declared safe to drink.
The contaminated water is still flowing downstream, and is expected to reach the Russian city of Khabarovsk next week.
Although the toxic spill is dissipating as it goes, Chinese authorities have offered to do whatever they can to stop major pollution in Russia, even suggesting building a temporary dam on the river.