1. My water cooler is leaking. What could be causing this? 99.9% of the time the leak is caused by a tiny hole the size of a pin prick in the bottle. Take the bottle off the water cooler, switch off & disconnect the power plug from the wall socket and contact us at hello@optimumh2o.co.nz. 2. How often should my water cooler be serviced and the water filter replaced? Your water cooler should be serviced every 6 months. The water filter should be replaced every 12 months to m