Doubts over fountain's future

A "fundamental flaw" in the design of the Diana fountain means it is likely to be closed for much of the summer, it emerged today.

The memorial, which cost £3.6 million to build and only opened two weeks ago, had to be closed last Friday after a Canadian mother and her young son needed hospital treatment after slipping in it.

Experts now say it is inevitable the fountain will need to be closed for long periods over the summer for cleaning.

Professor Rick Baterbee of University College London said: "It's a fundamental flaw with the design. They are using natural spring water, which is full of nutrients.

"Combined with sunlight that will create algae in a matter of days, and algae is very, very slippery. Anyone with any intelligence would know that."

Professor Baterbee warned that, without chemical treatment to prevent algae growing, the granite surface of the memorial created by Kathryn Gustafson would never be safe for paddlers.

He said: "The only way around this is to keep on scrubbing the stone clean. However, they will need to do this an awful lot, particularly when there is bright sunlight. The algae can grow in a matter of days." Water for the fountain is taken from a freshly drilled 200m-deep bore hole. This is stored in a holding tank before being used in the fountain.

Once the water has wound its way through the fountain, it is released into the Serpentine.

This means adding chemicals to the water is not an option, a spokesman for the Royal Parks, which controls the fountain, confirmed. He said: "We can't do anything to upset the natural balance of the lake. The fact we replace the water so often, and it is pumped in fresh from the bore hole also means that chemical treatment is not an option."

Officials claimed that paddlers and dog owners were adding to the hygiene problems. "We have put up signs, but people are still going in and even letting their dogs in", the spokesman said.

To combat the problem, the fountain will initially be shut every Monday morning for cleaning. But experts warned that the bacterial build-ups would get worse, causing discolouration of the white and pale grey surfaces as well as the risk of serious accidents.

Professor Baterbee said: "This is a perfectly natural reaction, and it can't be stopped."

Filters are also in place to catch leaves and other debris that may get into the system. The filters are meant to be checked regularly in order to stop any possible blockages, but they appear to have failed during the first few days causing flooding.

Today the public was being kept well away as the fountain is surrounded by metal barriers. Royal Parks staff are trying to cut grooves into the granite steps in a desperate effort to reduce the risk of slipping.

Ms Gustafson was unavailable for comment.