Water Supply in Buildings: The Regulation That Protects Public Health

When building or renovating a home in Portugal, one essential element often receives less attention than it deserves: the potable water supply system. This vital component is governed by the General Regulation for Water Supply, referenced in the General Urban Buildings Regulation (RGEU), approved by Decree-Law No. 38 382 of 7 August 1951. The regulation ensures that all buildings have an adequate supply of potable water, in sufficient quantity and quality to meet the dietary and hygiene needs of their occupants.

"Potable water distribution systems must be designed so that the water flows directly from the supply source to the outlets, without prolonged stagnation in storage tanks."​

What Is the General Regulation for Water Supply?

The General Regulation for Water Supply sets out the technical and sanitary conditions governing the supply of potable water to buildings in Portugal. Although referenced by the RGEU, this specific regulation defines strict standards intended to safeguard public health by ensuring the quality and safety of distributed water.

Its primary objective is straightforward yet critical: to guarantee that all buildings have a sufficient supply of potable water for residents’ consumption and hygiene, free from

contamination and infiltration that could compromise sanitary conditions.

Scope of Application

The regulation applies to:

• All new constructions – water systems must comply from the design phase.

• Reconstruction, extension, and alteration works – existing systems must be assessed and updated as needed.

• Residential, commercial, industrial, and public-use buildings – ensuring minimum sanitary conditions across all types.

• Mandatory connection to the public water network – all buildings within reach of a public network must connect via private service pipes, except in cases of legal exemption.

Historical Context: From Urban Sanitation to Modern Regulation

Before the RGEU came into force in 1951, the 1903 Urban Sanitation Regulation governed water supply and drainage in basic form. As urbanisation and public health awareness advanced, it became necessary to establish a more comprehensive and demanding framework. The 1951 RGEU introduced, for the first time, detailed technical provisions on:

• The design and installation of water supply systems

• Materials used in plumbing

• Protection against contamination

• Water quality and consistency

• Connections to public networks

Subsequent updates have maintained the regulation’s core mission: to protect public health and ensure dignified living conditions.

Main Provisions of the Regulation

1. Mandatory supply – Buildings must be provided with sufficient potable water for consumption and hygiene. Locations served by a public water network must include interior distribution systems connected privately to that network.

2. Protection of water quality – All water systems must be designed and operated to prevent contamination. Key principles include the separation of potable water systems from other water or drainage networks, maintaining isolated piping from waste systems, and installing proper backflow prevention devices.

3. Permitted materials – Only impermeable, durable materials that guarantee water purity up to use points may be used.

4. Distribution systems – Water must flow directly from the supply source to outlets without prolonged storage. Where storage tanks are unavoidable, they must permit full emptying and regular cleaning, and be protected from heat and contamination.

5. Wells and cisterns:

- Must be isolated from contamination sources and waterproofed along the upper walls.

- Surfaces around openings must slope away to prevent infiltration.

- Vent openings must be sealed against dust and insects.

- The use of wells or cisterns for domestic supply is prohibited when contamination risk exists.

Qualified Professionals

Implementation and oversight of water supply systems must be carried out by certified professionals:

• Design engineers – Licensed civil engineers responsible for designing compliant networks and signing technical responsibility statements.

• Site directors and supervisors – Ensure execution matches approved designs and legal standards.

• Contractors and builders – Certified by the Institute for Construction and Real Estate (InCI, I.P.).

• Certified network connection firms – Approved by managing authorities to connect buildings directly to the public network.

• Municipal councils and inspection bodies – Oversee compliance, enforce corrective works, and ensure safety and sanitation.

Summary Table

Aspect	Description
Definition	Technical norms for design, execution, and maintenance of potable water systems
Scope	All new buildings, reconstructions, and alterations across sectors
Legal basis	RGEU (1951) and updates
Materials	Impermeable, durable, safe for water quality
Connection	Mandatory link to public network when available
Professionals	Engineers, certified contractors, supervisors
Oversight	Municipal councils and inspection entities
Responsibility	Shared among designers, directors, contractors, and owners

Practical Recommendations

• Always consult a qualified civil engineer before installing or modifying water systems.

• Confirm that your building is connected to the public water supply network or has a legal alternative.

• Maintain updated documentation: project approvals, licences, and responsibility statements.

• Schedule regular maintenance to prevent system failures or contamination.

• Protect wells and cisterns through proper sealing, cleaning, and ventilation.

• Ensure potable water and drainage systems remain properly separated.

In Summary

The General Regulation for Water Supply is a cornerstone of public health and building safety in Portugal. It ensures that every property has an adequate potable water system, designed and built by qualified professionals under municipal oversight. Its enforcement on both new and existing buildings upholds high standards of hygiene, technical quality, and quality of life.