Disinfection Selection

Built water solutions continuous chlorination system

Those of us who have realised that we need continuous disinfection of a potable water system also know what happens next. The horrible question ... which one will I choose?! Well let's face the monster and discuss your options!

We are confident that we could defend any proposed generic disinfection process in a public forum. We are equally confident we could dismantle any proposed generic disinfection process in the same forum. Peer-reviewed scientific data support either argument - or both! What does that tell you? - well obviously it is all about context. Things work in the right application. The wrong tool rarely does the right job.

It is a well worn cliche that there is no single solution for disinfection. It is also a well worn cliche that Legionella and bacterial control is achievable. So selection of the right tools for the job is essential to success.

It is probably disappointing to an Facility Manager to have to consider what disinfection method to use. Immediately cheap looks good - but you still have the worries that 'you're paying for snake oil' or 'it costs too much' - and 'will I sleep better?'

So what are my options?

In the interests of sound sleep and balanced science here are some steps in selecting a disinfection process. Much as we are no fan of 5 step plans for anything - Here's a 5 step plan! The points below apply to the vast majority of disinfection systems used for building water (potable) systems (in alphabetical order so we show no preference):

Chlorine

Chlorine Dioxide

Copper /Silver Ionisation

Hydrogen peroxide

Monochloramine

Ultra violet light

Any one of these will fail in the wrong application. Beware anyone who tells you 'this is the only proven way of removing biofilm and controlling Legionella' - either they are ignorant or telling porkie pies!! Either way write them off the list!

So what do we do?

1) Do the leg work

If you have a water safety plan then it will probably help with this. The water risk management plan should already tell you who to talk to and their level of responsibility.

If you don't have a plan this may be very costly. Seek independent opinion (frankly, testimonials are not often really helpful!) and your potential provider should be happy to give you full access to their client base for comment. Be prepared to take some time doing the research. In the end it will pay off.

What is the process likely to cost a) to install and b) to maintain? Maintenance may be a big issue down the track and in some instances might be more costly than the installation.

2) Understand the Regulations

This may sound simple - but is the proposed process legal? Water Safety Regs are very specific about what can and cannot be introduced into potable water systems, and can be discharged to sewer.

The regs are also very specific about exposure thresholds for human safety and consumption. Is the process 'safe' ?

Once you know it is compliant you usually need to register the process with your technical regulator, department of health, minister (someone will want to know what you are doing) and get their approval.

It's your due diligence.

3) Understand the hydraulics

Is your system new or old?

Firstly, in old systems accurate hydraulic drawings are rare as hens teeth! This is a worry. Often there is an FM historical 'narrative' that will help here.

This links to water chemistry - but old systems with either historical corrosion or historical scale can make a real mess of your disinfection plans. The metals installed may hold the potential for all sorts of headaches; elevated lead, dezincified brass, galvanic corrosion..... In the worst case it can turn your water system into a water feature with unplanned outlets throughout the system!

In new systems - can you verify that the drawings really represent 'as built'? More often than not they won't. If you're still in 'hand over' it is well worth making sure they are accurate. ("As Built" doesn't necessarily mean "As Installed")

Are there special applications for the water?

Are residence times and dead legs in the system understood?

4) Understand the Water Chemistry

Yes, most people get phobic about chemistry! But if you're introducing a disinfectant then it is a chemistry issue!

This might make a blog on it's own - but here goes:

What does the supply water quality tell you?
Are metal oxides in the supply a problem?
Does the system receive other chemical treatments that need considering?
Is pH an issue?
Do you need a residual around the system?
What routine monitoring do you need to undertake?
Are there corrosion / scale issues?

Lots of these points can be answered by a good accredited water analysis and some fairly basic calculations. If your prospective supplier doesn't know what a Ryznar or Langelier index is; then they are probably not up to speed. After that a bit more digging may be needed to 'short list' your disinfection options.

5) Understand the contractor

What is their track record?

Ian McNeice as Bert Large, Doc Martin, ITV Studios.

Often in the industry you meet those those who went to the "University of Hard Knocks". Being 'around for a long time' is about their personal survival not your needs. Experience is something you should look for and value - but accompanying qualification is your safe point.

Do they have qualified expertise in:

hydraulics,

plumbing regulations

water chemistry

risk management

The emphasis here is on qualified. Personally, I would not let an unlicensed person do work on my home plumbing system. If that seems good to you, then why would you let an unqualified person do disinfection work on your system?

This comes back to the 'leg work' (above). Can the contractor provide documentation that demonstrates their capability and capacity? What accreditations do they have? Are they insured to cover the works?

These days your duty of care is to only let anyone on site who is appropriately trained and qualified for the task. This is about your survival not their needs!

Decision Time

So if you're happy with the answers you get from your 5 steps it's decision time. Remember that once the disinfection process has been installed you do not suddenly lose all liability and responsibility. You are still the responsible person - or delegate. It is still your responsibility to ensure maintenance of the system is performed and recorded. A good water risk management plan should make this a relatively simple and stress free process.

All of the mentioned areas above are what we specialize in, our business delivers industry leading processes, systems, training and support as well as market leading disinfection products that will enable you to manage and reduce risk of waterborne infection. We are an ISO accredited business and hold Systems, Safety and Environmental certification, please feel free to contact us if you would like to talk more.