A suburb in Sydney had its water woes backed-up last month, when heavy downpours caused sewerage problems for nearly 1000 residents.

Portaloos had to be rolled out by local authority Sydney Water due to the risk of overflowing toilets in hundred of properties. Finance Minister Andrew Constance says a specialist crew is carrying out a $3 million effort to repair the system by next February, including new valves and controllers.

Reports say 887 customers were inconvenienced and will now have the annual $570.76 wastewater service charge waived. A further 931 residents have been offered a $50 rebate.

Sydney Water Managing Director Kevin Young says the utility will work closely with residents, local councils and the NSW Government while a long term solution is delivered.