It's believed the site was broken into, storeroom locks cut and the pool filled with mains water over several days.

City of Greater Bendigo community wellbeing director Pauline Gordon said the incident was disappointing and dangerous.

"Someone has broken into the pool and cut the locks to two storerooms containing a ride-on lawn mower and dangerous pool chemicals, which usually require a licence to handle and can cause serious burns to skin,” Ms Gordon said.

“This increases the potential for theft and injury to the person or people who trespassed onto the site.

“The full pool is also a drowning risk to those breaking in or if the gates are left open, so the water will most likely be let go at a cost to ratepayers of $2000-$3000, although officers are assessing if it can be used elsewhere.”

Police are investigating and the Maple Street site will now be manned by security staff.

The break-in comes a week after council voted for the second time to close the pool.

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