They say that New Zealand is God’s own, a special country with all the benefits that nature bestowed on us, most especially - abundant water. That’s certainly been the case for the last 100 years and until recently, water taken for granted and delivered in reticulated pipework infrastructures to most domestic and commercial users has provided the backbone for fire sprinkler systems, now totalling some 7000 in New Zealand. I would imagine that no one would deny the benefits. Sprinkler systems provide personal life protection to tens of thousands of New Zealanders in their business premises and homes every day. They provide protection for a number of New Zealand’s very significant infrastructures assets, not to mention many other everyday businesses, thereby providing ongoing business continuity and improved insurable risk.
Now at this stage, and I know this might sound strange, but fire sprinkler systems do not, in the main, use very much water. They certainly don’t use water like you see in the Hollywood movies where all the heads in a building go off simultaneously, because it takes a certain amount of concentrated heat to set a sprinkler head off and this is usually only over the seat of the fire itself. In fact, if there were no sprinkler systems present in any given building where a fire was involved, (there are at least two fire saves per week from sprinkler systems in New Zealand) the resultant use of water by the NZ Fire Service to fight the fire, and the environmental damage from the fire itself, would be significantly greater than if a sprinkler system was present and controlled the fire as designed.
Back to my point that fire sprinkler systems do not use very much water at all.
While we have fire sprinkler system saves every week in New Zealand, most fire sprinkler systems sit passively waiting, day by day, minute by minute, to provide this huge assurance of personal life and property protection while the general population goes about their daily life. However, what these fire sprinkler systems do require, and what has been adequately provided over the last 100 years (in most cases) is the ongoing potential of water pressure and flow to meet the needs of the fire sprinkler system. I might be drawing a long bow here, but my point is that most of the requirement is potential, while at the same time actual water use itself is very very low. I make this point because water is a precious commodity in this world and I do not want people thinking that fire sprinkler systems sit there continually using this resource wastefully or without conscience.
As mentioned, fire sprinkler systems need water flow and pressure potential, but in reality use very little of New Zealands’ water resource. The infrastructure that has provided this potential for the last 100 years is our everyday town and city water mains and what a wonderful job they have done.
Water supplies in general have provided pressure in the 500 – 700 KPa range with volume often around 2000 – 4000 litres per minute and more. This potential has had a huge benefit for the New Zealand economy because it has allowed the vast majority of sprinkler systems to be built cost effectively, and using these town main water supplies has meant we have had little requirement for the additional cost of pumps or water tanks or the physical room that these would need. I should probably also mention that the inclusion of pumps and tanks in general will also reduce the reliability of sprinkler systems and for the life of the sprinkler system considerably higher maintenance and running costs.
The problem we are currently facing is town main water supply systems for use by fire sprinkler systems are now at risk for two reasons.
1. Ageing Infrastructure
The first and most easily explained is age. These underground water mains have been installed in New Zealand towns and cites for up to 100 years and in some circumstances sections of the ageing infrastructure need more gentle management via intentional pressure reduction than others. This reduction is being managed by various Territorial Authority’s or Water Supply Authority’s (WSA’s) via pressure reduction projects which involve the installation of a series of pressure reducing valves in a given area. I am advised that the reduction of water pressure does allow these areas to reduce both system water losses as well as help extend the life span of the pipework. Both points are very important and easy to understand.
Equally however, it is important to note that sprinkler systems installed within these intentional pressure reduced areas may have their design criteria (based on the use of previously available water pressure), compromised, and could be rendered non compliant to their consented design thus not meeting Building Warrant of Fitness (BWOF) requirements. This is a significant concern for building owners, Territorial Authorities, the insurance industry and sprinkler system installation and maintenance companies and needs to be closely managed before any intentional water pressure reduction project go ahead.
As noted in the start of this article fire sprinkler system are designed and installed to save life and property. This is a significant consideration when pressure reduction is considered. Presently the Fire Protection Association NZ has advised all Territorial Authorities in New Zealand of their commitment to work alongside those with these types of projects, to ensure that the integrity of installed fire sprinkler systems is not compromised.
2. Ongoing Responsibility to Supply Water Pressure and Flow
The more difficult issue to be resolved for the future of fire sprinkler systems off town’s mains water supplies is the ongoing “responsibility” to supply water pressure and flow. This is difficult and complex subject where the history of sprinkler system design and installation in New Zealand for the last 100 years (and documented as an acceptable and consented approach within New Zealand Sprinkler Standards) has been to use a de-rated percentage of the available water supply pressure measured at the time of installation.
This approach has served the economic environment well, in that it has allowed sprinkler systems to be installed without pumps and tanks and has provided cost effective management of fire protection in buildings. Alongside new intentional water supply pressure reduction projects to extended the effective life of water supply systems, then both considerations are valid and need to be considered.
Most water supply authorities (WSA) are beginning to take a very conservative approach to the provision of water supply (pressure and flow) for fire sprinkler systems. With the increasing complex nature of accountability, they are taking an approach where guaranteed water supply pressures are so low, that as a result, invariantly all fire sprinkler systems of the future would need to be installed with pumps and tanks. This, in itself, would be a very large increase in cost (as well as a number of physical space issues in buildings) for end users and if this was required for 100% of all newly installed fire sprinkler systems, would represent a significant future investment cost to New Zealand infrastructure.
In my mind, this issue needs to be researched and resolved with help from Central Government. I do not believe that any party have special rights that make the other parties position invalid. I do believe however, that “in general” most water supplies will never be reduced to the minimum guaranteed water supply pressures being advised by WSA’s so there needs to be fair debate and accommodation of risk to the parties involved. Without this, the additional cost to New Zealand infrastructure, based on a conservative no risk approach by WSA’s will be significant.
In summary, the future use of fire sprinkler water supplies via town’s main systems in New Zealand will change, but there is a challenge to establish an approach that balances all the factors involved. It will possibly be more important to take a more conservative approach to the use of town’s main water supplies than is presently allowed within New Zealand Fire Sprinkler Standards.
While WSA’s may not be able to guarantee the use of these pressures, and provided building owners of new systems understand the risks of using the available (de-rated) water supply, a continued use of towns mains water pressure and flow should be allowed. If, due to circumstances, water supply pressures lower such, that on some systems further fire system amendment or a fire pump installation is required in the future, this cost will need to be meet by the building owner. The alternative is to install fire pumps and tanks in the building owner’s premises in the first instance (even though suitable water supply pressure and flows are available) and this cost would have been expensed anyway, although at that time I would suggest unnecessary. This issue needs to be resolved at the highest level.
There are cost savings to be made by WSA’s who wish to use reduced pressures and this is important. There could be additional and unnecessary costs, which would be borne by building owners who cannot use (to a reasonable agreed level) the available water supply pressures and flows. Both aspects count as a cost to New Zealand as a country and needs to be considered and managed. Let’s get on with this consideration and find a way forward for the betterment of all.
Ross Aitken
General Manager Installation and Technical Support
Chubb New Zealand Ltd
FPA Chairman, Water Supply Sub-group.