Municipal water

And ... what's the question? Which municipality? Builders always opt for what's best for them...

The first thing to do is to contact the Serviços Municipalizados of your Camara Municipal and ask how much it will cost to connect to the water grid. I don't know where you are in the country, but usually there's only one water service supplied by the Serviços Municipalizados of your Camara and it won't cost that much to get connected.

If your home has a Licença de Habitaçao (habitation license) it will not be a problem to connect to the grid but if you are living in an illegal building such as a barn or illegal conversion done without planning permission and licenses, you may be in for a big hassle.

The way to find out is to ask the Camara, take your property documents with you.

  ̶C̶h̶i̶n̶e̶s̶e̶ ̶   Portuguese whispers  "  but our builder said the municipality said " 

From experience many things in Portugal involving different offices/people/online forums often give you different informations and local authorities etc may also have different interpretations of their responsibilities and how they implement them so to avoid messing about and wasting time you need to go to directly in person to whichever department responsible in the Camera and sort it out.

I don't know what's it like in Portugal, but in other countries I've lived it's down to the owner of the property to install utilities.

I don't know what's it like in Portugal, but in other countries I've lived it's down to the owner of the property to install utilities. - @SimCityAT

"Water company" to property boundary usually watermeter sited in/on front wall from water meter to/inside property the property owner's responsibility,