Details revealed as the Coalition attempts to push further water charge legislation through the Dáil show Siptu is attempting to gain the extra payment for the firm’s 2,000 workers despite Environment Minister Alan Kelly insisting he does not want a “bonus culture” to take hold.

Under moves confirmed by both Siptu and Irish Water, the union is to go to the Labour Relations Commission on behalf of its members, seeking that the bonuses — expected to reach into millions of euro — be paid out from next month.

This is because of what the union says is a previously agreed deal during the setting-up of Irish Water, which has since been reneged upon, due in part to political pressure.

The bonus payments —which Irish Water insists on calling performance-related awards — were introduced under a new pay model at its parent company Ervia in 2013, before being inherited by Irish Water when it was set up.

After a public outcry over the payments last year, the expected transfer of the money was delayed last year.

While sums for 2014 work were due to be handed over earlier this year, the move did not happen, with Irish Water’s board saying it would not be appropriate for this to take place — a position backed at the time by Mr Kelly.

However, Siptu official Adrian Kane told RTÉ’s This Week programme that union members have now lost patience with what they believe is a breach of their contractual entitlements, leading to the imminent LRC showdown which Irish Water said will take place on July 13.

While the firm has repeatedly insisted the bonus scheme is cheaper compared to the alternative increment-based pay model, it has faced criticism over the funds and the fact that some workers considered to “need improvement” can benefit.

When the issue arose late last year, Mr Kelly insisted he did not want a “bonus culture” to develop, a view his spokesperson repeated when contacted last night.

The Irish Water bonuses issue comes at exactly the wrong time for Government, as it attempts this week to pass through a series of amendments to the initial legislation governing the controversial body.

The changes — outlined in the Environment (Miscellaneous Provisions) Bill, which deals with a series of department-related matters — include allowing landlords to evict tenants who do not pay charges; banning house sales unless bills are up to date and introducing a database for those who have paid.

The bonuses issue has also emerged at a time when Irish Water and Government officials are attempting to ensure the firm is able to pass Eurostat financial tests in September showing it is financially sustainable.

Irish Water has to date refused to detail how many of its 1.32m registered customers have paid their bills, rejecting a Freedom of Information request from Socialist Party TD Paul Murphy for “commercially sensitive” reasons.