The school recently welcomed a new addition to the school grounds 'Tanky' - a 10,500 litre water tank - to help maintain the school's plant life and teach students about rainwater harvesting.

The $5100 tank was installed with funds from Shellharbour City Council, who allocated $2500 from its Small Environmental Projects Fund, and the St Paul's Parent and Friends committee.

St Paul's teacher Wendy Carter said Tanky helped "make the school green".

"We have had a problem keeping the trees alive out the back because there was no source of water," she said.

"We've had big losses with trees. We plant every year for National Tree Day and we try our best.

"One year we planted 120 trees but we just couldn't keep them going.

"The tank is now at the back of the school, and it is giant and attached to five different taps along the fence-line which gives us much better access."

Ms Carter said Tanky would also educate and teach the students sustainable practices and water conservation.

"By collecting rainwater, kids can see it's clean and precious and not to be wasted," she said.

"We are hoping to introduce a garden or maybe a fruit orchard, to try and get students more hands-on with natural foods not just packaged food. We are very waste-free."

Students created a new section in the school's newsletter called Tanky Times to report on water levels and share water conservation tips.