A sprinkler system supplied by the municipal water system: yes, it is a viable solution, but only if specific documentation and liability requirements are met. Below, I explain what to expect, what to ask for, and what to do if you cannot ensure the required continuity.*
Table of Contents
When Is a Direct Connection to the Water Supply System Permitted?
A sprinkler system can be connected to and supplied directly by the municipal water supply. However, feasibility is not simply a matter of “it can be done”; the key issue is who formally guarantees that the water supply will be continuous and reliable enough to meet the system’s requirements.
In practice, before choosing the municipal water supply as your water source, you need to consider two aspects:
- regulatory compliance (as referenced in UNI EN 12845);
- Assumption of responsibility through statements/certifications.
UNI EN 12845: What Do Sections 9.1 and 9.2 Specify?
The option of supplying the system from the public water supply is mentioned in UNI EN 12845 (sections 9.1 and 9.2).
This means that the water supply system is one of the options being considered for the sprinkler system’s water supply. However, in the actual management of the project, the decision cannot be based solely on the existence of this option: it is necessary to verify that the connection is accepted by the utility provider and that there is a demonstrable and sustainable guarantee of continuity and reliability.
Authorization from the funding agency (Note 2 of Section 9.2)
In addition to the reference to sections 9.1 and 9.2, the provisions of note 2 to section 9.2—which concernthe utility’sauthorization for connection —must be taken into account.
In practical terms, this step boils down to a simple but crucial question:
Does the managing authority authorize the direct connection of the sprinkler system to the water supply network?
Without this prerequisite, the plan to supply water from the municipal water system cannot be properly implemented, because the administrative and operational “green light” for the interconnection is lacking.
Declaration of Continuity and Reliability (UNI EN 12845 8.1.2)
Assuming approval for the connection has been granted, the next step is the declaration. Based on the above, the operating entity must issue a declaration guaranteeing the continuity and reliability of the supply (see UNI EN 12845 8.1.2).
This statement has a very concrete meaning: it is not enough to have “water available”; rather, there must be an explicit guarantee that the supply will be consistently adequate to meet the plant’s operational requirements.
If this guarantee is formally provided by the water utility, a municipal water supply remains a sustainable option.
If the declaration is not received: guidelines from the “Plant Decree” 4.1
If the managing entity’s declaration is missing, the provisions of Decree 4.1 on facilities apply, which (as stated in the text) indicates that the availability of the service may be certified by:
- statistical data from previous years, to ensure service continuity;
- in a manner similar to that specified in UNI 10779 for water supply.
In addition, it is specified that certifications regarding the continuity of the water and/or electricity supply may be issued by the utility providers or by a fire safety professional.
Therefore, if the managing entity does not issue the guarantee, the viable “alternative” is the professional’s certification, based on the available information as described above.
Case Study: 10,000 liters per minute for 2 hours
In the case described, the estimate is 10,000 liters per minute for at least 2 hours. The question is: Can the utility company guarantee a continuous water supply at that flow rate without interrupting service?
The answer cannot be given “on a whim,” because (given the nature of the issue) a formal commitment is required:
- or through a statement from the operating entity regarding the continuity and reliability of service;
- or by means of a certification from a fire safety professional, guaranteeing that the water supply system is capable of delivering that flow rate for two hours at the design head.
The key point is not just “getting connected,” but obtaining (or building) a body of documentation that supports the required claim of continuity.
When to Switch to a Tank and Pressurization Pumps
If neither the operating entity nor the professional is willing to assume responsibility for certifying the above, the consequence is clear: the idea of using the water supply system as a water source must be abandoned.
In that case, the recommended solution is to switch to a system with:
- tank
- pressurization pumps
The goal here is to have a power supply that does not depend on the (uncertain) ability to maintain the continuity and reliability of the water supply system over time in relation to the sprinkler system’s needs.
Operational Checklist for Project Managers
To make the right decision about whether or not to install a water supply system, you can use this checklist:
- Verify that the sprinkler system can be supplied by the municipal water system (see UNI EN 12845, sections 9.1 and 9.2).
- Obtain approval for the connection from the utility provider (see Note 2 in Section 9.2).
- Request a declaration of continuity and reliability of supply (as specified in UNI EN 12845 8.1.2).
- If the declaration has not been issued, evaluate the certification process indicated (see Section 4.1 of the Plant Decree and continuity with regard to UNI 10779).
- If you are unable to obtain a declaration or certification of responsibility, use the alternative solution: a tank and pressurization pumps.
Conclusion
A sprinkler system supplied by the municipal water system is possible, but in practice, the decision depends on authorization to connect to the system and, above all, on declarations or certifications that guarantee the continuity and reliability of the water supply. If no one can formally assume this responsibility, it is necessary to switch to a storage tank and pressurization pumps.
