Plans for the UK's first "water cremation" service are on hold amid concerns about "liquefied remains of the dead going into the water system".
Sandwell Council in the West Midlands has been granted planning permission to offer the service, which is claimed to be environmentally friendly.
But Water UK says it is "not convinced" and Severn Trent Water has refused the council a "trade effluent" permit.
The cremation company Resomation says waste water does not contain human DNA.
On the company's website its founder Sandy Sullivan explains that after the cremation, liquid is "safely returned to the water cycle free from any traces of DNA".
But a source at Water UK, a membership organisation that works with water companies on industry standards, said it had "serious concerns about the public acceptability of this".
"It is the liquefied remains of the dead going into the water system. We don't think the public will like the idea."
The process of "water cremation" involves a body being placed in a metal chamber, where it is reduced to liquid and ash using a process known as alkaline hydrolysis. The process, which takes three to four hours, has not yet been used in the UK, although it is operational in a number of US states.
Resomation says the process produces a third less greenhouse gas than cremation, needs a seventh of the energy and allows for the complete separation of dental amalgam and bodily implants for safe disposal. Mercury from crematoria is believed to be the cause of 16% of UK airborne mercury emissions.
Sandwell Council, in Oldbury, West Midlands, which is working to offer water cremation at Rowley Regis crematorium, said it hoped to "offer people more choice".
Severn Trent Water said it was looking for government guidance as "there is no industry standard". In March it refused the council the trade effluent permit, which relates to what can go into sewers.