The role sanitizers and bather hygiene play in healthy water

by jason_cramp | April 4, 2016 12:30 pm

By Ellen Meyer

[1]

The primary goal of water treatment is to help protect swimmers from disease. Of course, it is important to protect the pool as well, but bather health is the first priority. This article will focus on the adverse health effects that can result from poorly treated pools and how to prevent them.

Before getting into the actual illnesses that can occur, the codes and laws referenced throughout this article that help prevent swimmer injury and illness should be reviewed first.

There are two main standards/codes that cover most pool and spa/hot tub care issues. In the U.S., the standard that addresses water quality is ANSI/APSP-11, American National Standard for Water Quality in Public Pools and Spas. The other standard, which is still relatively new to the industry, is the Centers for Disease Control and Prevention’s (CDC’s) Model Aquatic Health Code (MAHC). The MAHC does not cover residential pools and spas/hot tubs, but focusses on the design, construction, and operation of public facilities.

APSP standards and the MAHC are neither laws nor regulations that are enforced by any regulatory authority. Instead, they are standards/codes that not only serve as industry guidelines, but local public health authorities incorporate some of these standards/codes into laws.

Laws to regulate public pools come from the local and provincial/territory/state public health departments. Public pools are regulated and inspected by local public health authorities. These authorities, which could be city, regional/county, or provincial/territory/state public health agencies, write and enforce these health codes.

Laws used to regulate chemicals used in recreational water come from the Pest Management Regulatory Agency of Canada (PMRA) and the Environmental Protection Agency (EPA) in the U.S. PMRA and EPA regulate chemicals that kill pests. Pests can range from insects that damage crops to the bacteria that can be found in a pool. Any chemical that claims to sanitize a pool, kill bacteria or algae, or do anything else to prevent, destroy, repel, or mitigate any living organism in a pool or spa/hot tub must be registered with either agency in their respective countries. To obtain a registration, the manufacturer of the chemical must first provide data showing the product works and will not cause unreasonable adverse harm to people or the environment when properly used, stored, and disposed.

Now with that out of the way, it is time to talk about bugs and disease. These are not exactly pleasant topics, but they are important to understand.

Table 1

Group	Species	Typical Health Effect	Outbreaks*	Cases*	Hospital*
Bacteria	Pseudomonas aeruginosa E. coli Shigella sonnei Legionella spp.	Rash Diarrhea Diarrhea Respiratory illness	2 (4) 2 1 9 (2)	16 (56) 21 5 33( 52)	0 (0) 5 1 18 (1)
Parasites	Cryptosporidium spp. Giardia	Diarrhea Diarrhea	36 1	874 21	44
Viruses	Norovirus	Diarrhea	2 (2)	122 (21)	0 (4)
Chemical	Chlorine/chloramine	Respiratory/skin/eye irritation	3 (5)	57 (31)	0 (0)
* Values in parentheses are not confirmed to be the specific pathogen.

Measuring disease outbreaks

[2]

The CDC provides a survey of disease outbreaks in pools and spas every two years[3]. The latest survey covers 2011-2012. During this two-year period, there were 69 outbreaks in treated water (i.e. not a lake or river). A summarized breakdown of which organisms caused the diseases, how many outbreaks there were for each organism, and how many people were ill as a result is shown in Table 1 on previous page.

One of the major sources of contamination in pools and spas/hot tubs is bathers. Two of the organisms in this table may come from the environment (Pseudomonas and Legionella), but the majority are from swimmers. That said, bather hygiene is extremely important in minimizing pool water contamination. Showering immediately before swimming will not only minimize the number of pathogens entering the water, but will also lower the chlorine demand in a pool and/or spa/hot tub, as well as minimize disinfection byproducts.

What is the dirt on bathers?

How much contamination could possibly come from swimmers? Charles Gerba, and other researchers, have asked this exact question and provided the following data. Gerba’s study estimates an average of 140 mg (0.14 g) of fecal material is contributed to the water by each swimmer[4]. Keep in mind, however, this value can vary depending on the personal hygiene of the swimmer. That said, he estimates the range can be from a minimum of 0.1 mg (0.0001 g) for adults to a maximum of 10,000 mg (10 g) for a child.

This is one of the reasons why the CDC published its Share the Fun, Not the Germs leaflet[5] for distribution to swimmers to educate them on how they play a huge part in keeping a pool clean and safe.

Contamination can be minimized if swimmers shower before swimming, refrain from urinating in the pool and wash their hands after using the washroom. However, some contamination in the pool is inevitable; therefore, it is extremely important that there is a residual of a PMRA/EPA-registered sanitizer in all parts of the pool at all times.

By law, sanitizers and disinfectants must be registered with the PMRA/EPA to ensure their safety and efficacy.

Why is a residual important?

It is important to keep a sanitizer residual in the pool to prevent bather-to-bather disease transmission. There are a variety of techniques that can be used to kill bacteria and viruses (e.g. ozone, ultraviolet [UV] light, sterilization with heat, etc.); however, in a pool, it is also important to have a sanitizing agent in the water with swimmers.

As ozone, UV, and other in-line treatment systems used to kill bacteria and viruses are separate from the pool, a person using a pool with such a treatment system could still become infected if the swimmer comes into contact with the contamination in the water before it reaches the treatment system. To combat this, some residual sanitizer should always be circulating in the water.

Not only does a residual sanitizer need to be kept where swimmers are present, but also maintained in parts of the pool where there are not many swimmers (e.g. at the bottom of a diving well). A residual sanitizer should also be maintained at night and during periods of closure when no one is in the pool.

The reason for this is bacteria such as Pseudomonas and Legionella can grow and reproduce in an unsanitized pool. These organisms can form a slimy layer called biofilm. It is very hard for sanitizers to get into a biofilm and kill organisms harbouring there, so even if a sanitizer residual is re-established, it may not be able to fully sanitize the pool.

Sanitizers

It sounds obvious, but to sanitize a pool, a sanitizer is needed. There are numerous products that claim to kill bacteria or treat bacterial slime, but unless the product is a PMRA/EPA-registered sanitizer as indicated on the label, it is not a sanitizer. In the U.S., the only acceptable alternative to this is the use of an EPA-registered disinfectant. A disinfectant residual is also acceptable for sanitization of pools and spas/hot tubs.

Throughout the rest of this article, the word sanitizer will be used in reference to both sanitizers and disinfectants. Chlorine and bromine (Br) are the only chemicals registered by the PMRA for sanitizing pools and spas/hot tubs. In addition to chlorine and bromine, polyhexamethylene biguanide (PHMB) and some metal systems are registered for use in the U.S. by the EPA.

There are various forms of these chemicals, but these are the only sanitizers recognized by each agency for providing sufficient sanitization.

That said, each of these sanitizing chemicals have requirements for optimum performance. Those requirements are discussed below.

Chlorine

Chlorine activity is affected by pH, ammonia (NH₃), cyanuric acid (CNOH)₃, and other nitrogen (N)-containing contaminants. The effect of pH on chlorine can be seen in Figure 1 below.

To understand this graph, one needs to know the different forms of chlorine (e.g. chlorine gas, calcium hypochlorite [Ca(ClO)₂], trichloroisocyanuric acid [C₃Cl₃N₃O₃], etc.), release hypochlorous acid (HOCl) when added to water. Hypochlorous acid is the active sanitizer that kills bacteria in the pool. At low pH, all of the free chlorine in the pool is present as hypochlorous acid; however, at high pH, it splits into hydrogen ions (H⁺) and hypochlorite ions (OCl^–). The latter is not as effective at killing bacteria as hypochlorous acid. At low pH, the activity of chlorine is maximized, but low pH can also cause corrosion of pool surfaces and irritate bather’s eyes and/or skin. The recommended pH range of 7.2 to 7.8 is a compromise to maintain chlorine efficacy without causing other problems.

When bathers urinate or sweat in the pool, a variety of different chemical contaminants are contributed to the water. One of the primary components of sweat and urine is urea CO(NH₂)₂. When chlorine reacts with urea, it forms combined chlorine. The three main types of combined chlorine are monochloramine (NH₂Cl), dichloramine (NHCl₂), and trichloramine (NCl₃). Free chlorine is much more effective than combined chlorine. This is another reason why it is important for bathers to shower (removing any dried sweat from their bodies) and use the washroom before they enter the pool. People can still sweat as they swim, so it is important to know how to get rid of chloramines once they are formed.

The most common way of doing this is to perform breakpoint chlorination. To achieve breakpoint chlorination, chlorine is simply added at a dosage that is 10 times the combined chlorine concentration. This dosage is usually sufficient to fully oxidize the nitrogen in the chloramines to nitrogen gas.

The third factor that has a large impact on chlorine efficacy is cyanuric acid (CYA). This stabilizer is added to pools to help prevent sunlight from destroying chlorine. When chlorine is bound to cyanuric acid, it can be released quickly to perform its job of sanitizing. However, as the cyanuric acid concentration increases, chlorine effectiveness slows down.

Over the years, many studies have been performed demonstrating the adverse impact of cyanuric acid on chlorine effectiveness in pure distilled water as well as samples of water taken from pools. The effect of cyanuric acid on chlorine effectiveness has been seen with bacteria, viruses, and protozoa such as Cryptosporidium (Crypto).

The CDC recently published an article where it examined the effect of cyanuric acid on kill rates for Crypto.⁴ It found with 50 parts per million (ppm) cyanuric acid, it was unable to achieve a targeted 99.9 per cent reduction of the parasite. With 20 ppm cyanuric acid, the amount of time needed to kill Crypto was approximately 10 to 20 times longer than without cyanuric acid. Since cyanuric acid can affect the ability of chlorine to sanitize pools and spas/hot tubs, its concentration should be monitored and controlled. The ANSI/APSP-11 standard and the MAHC currently set the limit at 100 ppm. This is a hotly debated topic, however, and some public health authorities are lowering their cyanuric acid limits below 100 ppm in an effort to help avoid bather illnesses.

Bromine

Bromine sanitizers are much less susceptible to high pH values than chlorine. The active form of bromine (HOBr) (shown in Figure 2 above) is present at much higher pH values than chlorine. This is one of the reasons why bromine is so popular in spas/hot tubs, where the pH tends to drift up more quickly due to the high temperatures and aeration of the water.

Like chlorine, bromine will react with bather waste to produce bromamines, but bromamines are almost as effective in killing bacteria as free bromine.

A disadvantage of bromine, however, is it cannot be stabilized to prevent destruction by sunlight. It is not at all stabilized by cyanuric acid, and a molecule called hydantoin (C₃H₄N₂O₂), which is used to provide bromine is only slightly effective in stabilizing it.

Polyhexamethylene biguanide

Polyhexamethylene biguanide (also known as PHMB or biguanide) is a non-chlorine, non-bromine sanitizer. Since it is not an oxidizer, a separate oxidizer must be added to eliminate contaminants that are not removed by the filter. Hydrogen peroxide (H₂O₂) is typically used in these systems.

Polyhexamethylene biguanide maintains its activity over a very broad pH range (much broader than pool and spa/hot tub operating pH values). Its activity is also not affected by sunlight, bather waste such as urea, or by stabilizers such as cyanuric acid. However, it is incompatible with some common pool chemicals, including:

• Metal ions (e.g. copper algaecides, ionizers, metal cartridge systems, etc.);
• Phosphates and phosphonates (e.g. many chemicals that are used to prevent staining and scaling in pools and spas/hot tubs); and
• Chlorine and bromine (e.g. chlorine shocks should never be used in polyhexamethylene biguanide pools).

Metal systems

Some metal systems are registered as sanitizers by the EPA and some are not, so care must be used in choosing a metal sanitizing system. Most systems are based on the use of silver (Ag) and copper (Cu). The efficacy of these metals is extremely dependent on water parameters, which can cause them to precipitate into insoluble forms that are not effective and can cause stains. For instance, both can be made insoluble at high pH. Silver also becomes insoluble in the presence of chloride (i.e. what is left after active chlorine does its job), while both can precipitate with phosphate (a breakdown product of phosphonate-based metal control agents). Another factor to remember is the kill rate of metals is much slower than chlorine or bromine, as shown in Figure 3 below. This is why metal systems typically require the presence of at least 0.5 ppm of chlorine.

No matter which sanitizing system is used, it is important to follow the label directions for that particular product.

Figure 3: CT values
Organism	Chlorine, typical CT* values, ppm min	Silver CT values, ppm min
Bacteria	0.02-1	E. coli 2-45[6] Legionella 115
Virus	0.5-30	>5000[7]
* being the disinfectant concentration multiplied by the contact time

Summing things up

The two most important ways to keep a pool and/or spa/hot tub clean and healthy are to minimize contamination by encouraging proper bather hygiene and to maintain a residual of a PMRA/EPA-registered sanitizer in all parts of the pool and/or spa/hot tub at all times.

[8]Ellen Meyer is technical service manager with Lonza, a global supplier of pool and spa/hot tub chemicals. She has chaired the recreational water quality committee of Association of Pool & Spa Professionals (APSP), and currently serves on the technical review committee of the Model Aquatic Health Code (MAHC), and is a member of the NSF International task group for pool chemical evaluation. She can be reached via e-mail at ellen.meyer@lonza.com[9].

Source URL: https://www.poolspamarketing.com/trade/the-role-sanitizers-and-bather-hygiene-play-in-healthy-water/

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