Explainer: cleaning our rock pools

It can be frustrating when you visit your favourite rock pool and instead of the pristine dip you were hoping for, you find it’s a little murky. It probably makes you wonder how, and how often, our rock pools are cleaned.

Here’s answers to some of the regular questions we get here at Council about our rock pools:

During the summer season every rock pool is emptied subject to sea conditions and cleaned once a week. Each pool has a set day/night so the community know when to expect it. 

Due to its high usage, Dee Why pool also has an additional drain and flush after the weekend.  

You can find the cleaning roster for your favourite pool here.

Occasionally crews need to clear the drainage valves when they are blocked with sand to allow the pool to empty. The pool is then drained as much as possible. Sometimes sand or weed build up, high low tides and prevailing surf conditions can make a full drain impossible.

From there a high-pressure device is used to remove algae build up from the walls, pool floor, ramps, stairs and railings. Sand and seaweed is swept to the value to allow it to be washed out to sea. If the pool has not been able to be completely emptied due to high low tides or large seas it can be difficult to access all surfaces. 

Additional earth moving machinery is employed as required to remove excess sand or debris.

There are a number of factors which feed into when we clean the rock pools. They are emptied and cleaned on the low tide as this is the only time that we can physically empty the pools. Our crews regularly work through the night as our aim is to reduce the inconvenience on the community and keep pools open.

Crews work through all weather conditions, stopping only if it is not safe to continue, such as during a lightning or hail storm or in the event of large swell.

If our crews have not been able to totally drain the pool, it can take a day to flush out some of the algae from the clean. As such Day 2 after a clean is generally the best time for swimming.

The other factor that effects the water quality of the rock pools after the clean is the size of the swell. Rock pools benefit from a moderate to large swell which flushes the pool naturally between cleans. When there is prolonged periods of low swell the natural flushing does not occur as there is not sufficient turnover of the water.

The Environment Protection Authority recommend “as a general precaution, swimming at Sydney's oceans beaches should be avoided for up to one day after heavy rainfall or for as long as stormwater is present. The most obvious signs of stormwater pollution are water discolouration as well as debris in the water and on the tide line.” The EPA provide a daily water quality update. 

We have two internal crews operating on a north and south split, following a weekly cleaning roster that has been in place for many years.

From time to time when larger excavation equipment is required Council engage contractors to perform this task under our rock pool cleaning team’s supervision.