Orange City Council announced the switch on Wednesday, with water supplies to dip below 40 per cent capacity, one month later than predicted due to contributions from the stormwater harvesting system at the Macquarie Pipeline.

Under level four, lawn watering will not be allowed, with no new turf to be installed, and garden watering will be limited to Wednesdays and Sundays between 4pm and 6pm.

Micro-sprays and soaker hoses will be allowed within those hours, while handheld hoses with trigger nozzles will be allowed for half-hour stretches.

Hoses will also be allowed for washing cars, provided the car is parked on the grass, with councillors considering the elderly.

Cr Kidd said lawns would need less water as autumn and winter progressed and frosts took hold.

"We're already having very heavy dews and you'll find the water use is very low because if you've got kikuyu or buffalo or any of those, they'll start dying off anyhow," he said.

"While we're moving from the system of watering every other day morning and night, to the much tougher approach of two hours on two days a week, we want to be fair to people who still want to use a hand-held hose."

Evaporative airconditioners will only be allowed to run between 7am and midnight, showers will be capped to five minutes and washing machine use will be limited to full loads.

Cr Kidd said his household averaged two-minute showers.

"I would say this to people, put a timer on and see - five minutes is a hell of a long time in the shower," he said.

"It's important that we respond to the dropping storage levels and with the drop below 40 per cent of capacity we all need to tighten the belt."

With water usage during level three restrictions mostly well above the recommended 220 litres per person per day, Cr Kidd said the peaks occurred during a hot summer and household consumption dropped in the winter months.

Level five restrictions remain possible if the dams reach 35 per cent capacity - they would introduce Sunday watering with buckets only and three-minute showers, and ban washing cars at home and filling swimming pools and water features.

Cr Kidd believed level five would be unlikely, although businesses would still be able to function if they did come into force.

At Tuesday's meeting, the Central West Water Alliance's Cyril Smith asked for trigger points to be reviewed given they did not take into account stormwater harvesting or the pipeline.

Cr Kidd agreed the review should occur to see whether changes were needed for the trigger points themselves or what usage was allowed at different levels.  

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