Your general obligation under the Residential Tenancies Act, 2006 is to maintain the property and to comply with all health, safety and housing standards. There are no specific guidelines that outline how a landlord should remedy any specific problem that may arise in the area of repair.
There is a separate procedure for long term planned renovations that require building permits and vacant possession by the tenant, but for emergency type scenarios such as yours, there is often the involvement of insurance companies and uncertain timelines because of contractor availability, etc.
As with any situation that requires water or electricity supply shut off, temporary inconvenience is a standard part of the process for all concerned. If you can offer your tenant somewhere else to live at your expense during the time of the repair, then this seems reasonable. If the tenant suggests a hotel or other accommodation, which is what an insurer often provides in similar situations, then you will have to reach some kind of compromise if you want to get on with getting the work done.