A group of Eugowra primary school students has developed a flood sensor that will alert residents to rising waters.

Students at St Josephs Eugowra have worked with community members and engineers - and grappled with ultrasonic sensors, Microbits and programming to develop their prototype - which they're presenting this week to a national Catholic schools competition in Brisbane.

The STEM MAD competition is Science, Technology, Engineering and Mathematics challenging students to Make A Difference - and that's something these students are determined to do after losing their school in the flood event that devastated their community on November 14, 2022.

Senior students Olivia, Belle, Sam and Zac have been charged with presenting the project, in a video you can watch on the school's Facebook page.

"Nobody knew how much water was coming because the existing devices had been damaged and all communications were lost," Belle explains in the project video.

"We wanted to create a simple warning system that would withstand extreme currents, and water depths, that could alert people to rising floodwaters."

Their work began with a look at past floods: how big they were and how people were warned.

"We surveyed the residents to answer some of our questions relating to flood history and created a timeline of all of our information," Olivia said.

"We also drew graphs to show the differences in flood heights across the years."

One of the things they learned was that the extreme wet conditions of 2022 had saturated the ground even before the severe storm of November 13, leading to the tragic events of the next morning.

Students looked at the catchment area, which gave them a good idea of the volume of water that flowed into Mandagery Creek, then toured town to look at historic flood heights in different locations.

The group visited a property with a flood warning device before grouping up to share their ideas, come up with a design and identify the materials needed to make it.

"We all wanted to use sensors to set off the alarm, so we need to learn how to program the Microbit," the students said.

"We decided to make a water turbine and a tilting alarm, but the prototypes were not successful, so we had to make changes to try and improve the result."

Principal Cathy Eppelstun said students had worked closely with the Science and Technology consultant for the Bathurst Diocese Catholic Education Office to develop their project, from concept through to the prototype that finally delivered the result they wanted.

Engineers working Eugowra's flood recovery committee also shared their expertise: the Rhelm team learned about the students' work through Mrs Eppelstun at one of the regular meetings and immediately offered to come to the school.

By this stage students had developed two prototypes, which hadn't been successful: Rhelm suggested either an ultrasonic sensor or laser, and these worked better.

The final design uses an ultrasonic sensor to measure water levels and sound an alarm at different heights, with solar panels added to make it more sustainable.

"Our system can help people evacuate early during floods and could be used in other flood-prone areas," the students said.

"The materials are inexpensive and simple to put together, so it can be manufactured simply.

"An app could be created to send a signal to a phone if people are away."

The importance of the project is close to home for the students presenting it.

"They lost every single thing you can think of," Mrs Eppelstun said.

"I think they can see a real purpose for this, this isn't something we're just doing for fun."

How they've grasped the technology has been one incredible aspect of the whole project, the other has been the understanding they have come to about how extreme the event of 2022 was when looking at Eugowra's historic floods.

"It's been, for all staff, parents and children, part of the healing process," Mrs Eppelstun said.

Students are back in their rebuilt classrooms this year but the work continues on the school, with the staffroom, staff toilets and library on the list for repair next year.