For the past six months, people who filled up their bottles with spring water from the tap have been asked to give 10c a litre to a fund for Dunedin environmental projects.
Speight's spokesman Chris Snow said while 409,000 litres of water had been taken in that time, only $5665 had been donated.
If everyone had donated, about $40,000 would have been available for groups protecting and preserving Dunedin's natural environment, he said.
With only 10% of people paying, it seemed people did not know why donating was so important, he said.
All the "tap" money went into the fund, with Speight's adding $ 25,000 a year.
Proceeds from the sale of reusable water bottles also went towards the fund.
In the first round of funding, Hawksbury Lagoon, the Dunedin Royal Forest and Bird Society and the Orokonui Ecosanctuary received funds for projects such as revegetation and audio attraction equipment for seabirds.
People spoken to by the Otago Daily Times at the tap yesterday said they were unaware of the option to donate, as the service had been free for so long.
Mr Snow said the company would not enforce the donation, but hoped people would support it, as it was for a good cause.
