Those companies, members of the Spanish technological association for water treatment (ATTA), offered the cooperation via the Spanish Embassy's economy and trade office.
The embassy and the Croatian Waters company on Tuesday organised a seminar which brought together about 100 representatives of Spanish and Croatian water management companies, counties and cities.
Ambassador Rodrigo Aguirre de Carcer said Croatia and Spain were quite similar in terms of water resources and tourism orientation and that Spain, because of its population and EU directives, had to work hard to improve standards and water supply, drainage and protection.
He recommended that Croatia use Spain's experience in that, saying it was reflected in a much lower water price than in north Europe, where there is much more water.
ATTA director Angel Cajigas said Spain drew EUR 5 billion from EU funds to "purify a lot of water", making it available to nearly the entire population.
About 80 per cent of Croatia's population is connected to the water network but only 44 per cent to the public drainage system and only 27 per cent of waste water is treated, which must be improved by 2018 and 2023 according to EU directives, Elizabeta Kos of the Agriculture Ministry said, welcoming cooperation with partners in the EU and funds from the EU, the European Bank for Reconstruction and Development (EBRD), and the World Bank.
Under the IPA programme, Croatia drew nearly EUR 200 million from the EU for this purpose in 2007-13. Two projects are under way, one of EUR 105 million with the EBRD for inland waters and a EUR 280 million project for the coastal water system.
Croatian Waters director general Ivica Plisic said the company expected to draw EUR 200 million annually in 2014-20.