The Fair Work Ombudsman said the organisation would repay the funds after entering into an enforceable undertaking.

The underpayments range from less than $1 to $380,000.

The FWO said it had started an investigation into Seqwater following media reports.

Seqwater said it had discovered about 790 employees were underpaid over many years.

“Many employees were underpaid because Seqwater incorrectly determined that it was not required to provide entitlements because they were on individual contracts,” the FWO said.

“Payroll system errors and process issues also caused underpayments.’

Most underpayments related to overtime but there were also underpayments for travel, on-call and call-back allowances, remote areas assistance, leave loading and even ordinary hour pay.

The workers were located throughout the southeast.

The underpayments must be repaid before February 2023 and FWO said further underpayments were still being qualified.

Fair Work Ombudsman Sandra Parker said that under the Enforceable Undertaking, Seqwater had committed to implementing stringent measures to ensure workers were being paid correctly.

“These measures include engaging, at the organisation’s own cost, audits of its compliance with workplace laws over the next two years,”  Parker said.

“Seqwater’s breaches and subsequent significant backpay bill demonstrate how important it is for employers to place a high priority on workplace compliance, including having a clear understanding of how any enterprise agreements apply and performing regular checks to ensure they are providing employees with all lawful entitlements.”

“Any employer who needs help meeting their obligations to their employees should contact the Fair Work Ombudsman for free advice and assistance.”