The office claims water was drawn down before a conservation order was issued
The Office of Public Works (OPW) has defended cleaning the Papal Cross in Dublin's Phoenix Park.
It comes as Irish Water is warning that supplies could be restricted until the autumn.
A hosepipe ban is set to be extended this week to Laois, Kilkenny, Limerick, Kerry, Galway and Waterford.
The ban came into force in the greater Dublin area on Monday, as reservoir levels continue to fall amid the ongoing heatwave.
In a statement, the OPW says the work "is deemed essential" in advance of preparatory works for the World Meeting of Families event in August.
It also says the cross has not been painted in over four years.
A spokesperson says: "The build works on site will commence at the end of July and the painting of the structure must be complete in advance of the start of the works.
"This event will be attended by approximately 500,000 people and viewed by millions from all around the world on television."
The OPW adds that the appointed contractor has being preparing for the works for the past number of weeks - and used "the minimum amount of water required".
"The water that was used was drawn off last week before Irish Water put in place a Water Conservation Order", the OPW claims.
"The contractor has indicated that no further water is required for the remainder of the works."
Pope Francis will visit the Phoenix Park on the second day of his Irish trip.