Almost 100,000 non-domestic customers of Irish Water are set to see their fresh water and waste water bills rise.
The move follows a decision by the Commission for the Regulation of Utilities (CRU) on new tariffs following a restructuring of the charging regime.
The increases have been criticised by organisations that support businesses here.
The CRU says the new charging structure will create a more equitable, simple, stable and transparent charging method of the 183,479 non-domestic customers here.
But according to figures the regulator has released, for many - but not all - such customers it will also bring considerably bigger bills.
85,088 or 46% of Irish Water non-domestic customers will see decreases to their bills.
They will move right away to the new charging plan.
A further 67,088, or nearly 37%, will also move to the new tarrrifs and see their bill increase by less than €250.
19,268 or almost 11% will pay between €250 and €750 more. They will also be eligible for a transition tariff over three years, the regulator says.
While the remaining 12,035 or nearly 7% will face bill increases of €750 or greater.
They will also be eligible for a transition tariff as well as a 10% cap on their annual bill increase.
"The CRU welcomes the introduction of national tariffs for non-domestic customers," said Laura Brien, Director, Water and Compliance at the CRU.
"This is a significant step in the transformation of Irish Water into a single public utility. These cost reflective tariffs will play an important role in encouraging water conservation."
According to the CRU, there is currently over 500 non-domestic tariff levels, as well as multiple categories, methodologies, applications, billing arrangements and billing cycles as a result of the old local authority water system.
The new non-domestic charges were decided after a consultation period and take effect on 1 May 2020, in order to give customers time to plan.
However, Dublin Chamber has criticised the increases, saying they will lead to businesses in the city paying significantly more for water.
This will heap further costs pressure on businesses in the Dublin region and hurt the region's competitiveness, it warned.
"The Dublin region will be disproportionately affected by the new water tariff structure, potentially undermining the region's economic competitiveness," said Aebhric McGibney, Director of Policy and International Affairs with the organisation.
"Dublin Chamber consistently warned the CRU about the unfair impact that the proposed tariff changes would have on Dublin businesses. It is disappointing to see that this information has not been provided."