Point-of-Entry Water Treatment

Contributor
Grant Robertson, B.B.A., CWT
Introduction

Since the implementation of the B.C. Drinking Water Protection Act in 2001 and the accompanying regulations in 2003, small communities across the province have faced a wide range of challenges in meeting the requirements of the legislation. In particular, many have struggled to get community support for conventional water treatment methods that would enable them to meet the water treatment requirements of the Act and Regulations.

The difficulty in obtaining community support for conventional treatment, largely due to the perceived negative aspects of chlorination, has led to considerable interest in point-of-entry treatment. At the same time, the emergence of new technologies that reduce maintenance frequency and improve compliance monitoring are making point-of-entry systems a viable option for many small communities.

Glossary of Terms
activated carbon

Absorptive particles or granules of carbon that have a high capacity to selectively remove certain trace and soluble materials from water. The carbon is usually obtained by heating wood, bone or vegetable material to create charcoal.

aesthetic

Qualities that are attractive to the senses (e.g., the pleasing appearance, taste, and smell of potable water).

bacteria

Microscopic living organisms that usually consist of a single cell. Most bacteria use organic matter for their food and produce waste products as a result of their life processes.

chlorination

The application of chlorine to water, generally for the purpose of disinfection, but frequently for accomplishing other biological or chemical results (aiding coagulation and controlling tastes and odours).

contamination

The introduction into water of micro-organisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the water unfit for its  intended use.

conventional filtration

centralized water treatment system, also known as conventional treatment, is a combined process of coagulation, flocculation, sedimentation (or clarification), filtration, and disinfection. It treats water in a central location and then distributes the treated water via dedicated distribution networks.

cryptosporidium

A waterborne intestinal parasite that causes a disease called cryptosporidiosis in infected humans. Symptoms of the disease include diarrhea, cramps, and weight loss. Cryptosporidium contamination is found in most surface waters and some groundwaters. Commonly referred to as "crypto."

distribution system

The equipment involved with the delivery of treated water from the treatment facility to the intended end-point user.

disinfection

The process designed to kill or inactivate most microorganisms in water, including essentially all pathogenic (disease-causing) bacteria. There are several ways to disinfect, with chlorination being the most frequently used in water treatment.

giardia

A waterborne intestinal parasite that causes a disease called giardiasis (GEE-are-DIE-uh-sis) in infected humans. Symptoms of the disease include diarrhea, cramps, and weight loss. Giardia contamination is found in most surface waters and some ground waters.

hardness, water

A characteristic of water caused mainly by the salts of calcium and magnesium, such as bicarbonate, carbonate, sulfate, chloride, and nitrate. Excessive hardness in water is undesirable because it causes the formation of soap curds, increased use of soap, deposition of scale in boilers, damage in some industrial processes, and sometimes objectionable tastes in drinking water.

NTU

Nephelometric Turbidity Units: a measure of clarity of water.

nephelometric

A means of measuring turbidity in a sample by using an instrument called a nephelometer. A nephelometer passes light through a sample, and the amount of light deflected (usually at a 90-degree angle) is then measured.

PPM

Parts per million. The number of weight or volume units of a minor constituent present with each one million units of the major constituent of a solution or mixture. Used to express the results of most water and wastewater analyses, but presently milligrams per litre (mg/L) is the preferred term.

pathogenic organisms

Organisms, including bacteria, viruses, or cysts, capable of causing diseases (giardiasis, cryptosporidiosis, typhoid, cholera, dysentery) in a host (such as a person). There are many types of organisms that do NOT cause disease. These organisms are called non-pathogenic.

pressure

A force acting on a given area. The pressure is calculated by dividing the force by the area over which it is acting. The unit of pressure is the Pascal (metric system) or pound per square inch (psi).

pressure gauge

Instrument used to measure pressure.

purveyor

A supplier or provider of water.

sediment

Solid material that settles to the bottom of a liquid.

solenoid valve

A valve that uses the electromagnetic principle to cause mechanical movement to control flow. In this way, the valve can be operated remotely by an electrical signal.

solution

A liquid containing a dissolved substance. The dissolved substance is called the solute. The liquid used to dissolve the solute is called the solvent.

surface water

All water naturally open to the atmosphere (rivers, lakes, reservoirs, streams, impoundments, seas, estuaries, etc.); also refers to springs, wells, or other collectors that are directly influenced by surface water.

TOC

Total Organic Carbon. TOC measures the amount of organic carbon in water.

turbidity

The cloudy appearance of water caused by the presence of suspended and colloidal matter. In the waterworks field, a turbidity measurement is used to indicate the clarity of water. Technically, turbidity is an optical property of the water based on the amount of light reflected by suspended particles.

ultraviolet (UV)

In water treatment, a specific wavelength of light produced by a device used for disinfection.

valves

A device which is used to control isolate or flow in a piping system.

virus

A very simple life form that only multiplies inside the living cells of a host; average diameter of 1/10,000 mm.

What is Point-of-entry (POE) Treatment?

Simply stated, Point-of-entry (POE) systems involve the installation of water treatment equipment on the main incoming water line in each and every home (and business) within the community, as opposed to treating the water at a centralized location prior to distribution. POE systems treat all of the water entering the home, except in some cases, where the water used exclusively for irrigation purposes is left untreated.

Point-of-entry treatment should be distinguished from point-of-use (POU) treatment, which involves the treatment of water only at a single faucet or application. 

Who Can Use Point-Of-Entry Treatment?

While POE water treatment has been commonly applied for many years in individual commercial operations, including restaurants, hotels, lodges, schools, and other public facilities, it has become a more popular alternative for small residential communities during the past decade.

The interest in POE treatment has developed for several reasons, most notably because of the emergence of new technologies in ultraviolet (UV) disinfection equipment. Newer UV sterilizers have reduced maintenance frequency, increased reliability, and improved compliance and performance monitoring. Concerted efforts to educate dealers, regulators and consumers; formalize installer and operator training; and establish a code of best practices in the industry have also created a better understanding of the capabilities of the technology and how it should be used.

Under the Drinking Water Protection Act, small communities with water systems that serve fewer than 500 individuals have the option to use point-of-entry treatment as an alternative to traditional centralized water treatment.

It should be emphasized, however, that regulators have discretionary authority to approve or disapprove of POE treatment and to waive construction permit requirements and certain operator certification requirements on a case-by-case basis. Regulators can reject POE treatment if they do not have full confidence that it will meet the requirements of the Act and Regulations and deliver results comparable to a centralized system. Regulators sometimes express concerns regarding the proposed treatment equipment itself, system governance, or the likelihood of successful system maintenance and operation. With the proper planning, however, these concerns can be mitigated.

Many small water purveyors view POE treatment as a means of sidestepping their treatment responsibilities under the Act and Regulations. Their initial thought is that if they can get everyone in their community to install a POE system, they will be absolved of their responsibilities. This is not the intent of the POE treatment option afforded to small communities. POE implementation requires a solid commitment of the water purveyor and the community it serves and may in fact require greater efforts to successfully implement than a centralized system.

Who Should Consider Point-Of-Entry Treatment?

An affirmative answer to any one of the following questions suggests that point-of-entry water treatment may be a desirable option for a small community:

  1. Does the small number of homes served by the water system, or another factor, make centralized water treatment prohibitively expensive?
  2. Is the majority of the water distributed by the system used for purposes other than domestic water supply (e.g., agricultural irrigation)?     
  3. Is there low confidence in the integrity of the distribution system (e.g., risk of contamination from within the distribution system due to aged pipes)?
  4. Are there any contaminants present in the water that require treatment for health reasons that are not easily addressed with conventional centralized treatment equipment (e.g., heavy metals, arsenic, uranium, sodium, nitrates, etc.)?
  5. Do the community residents have a strong aversion to traditional centralized water treatment due to a perceived aesthetic (taste/odour) issues?
  6. Does the source water contain an elevated level of organics that would be expected to result in the formation of harmful disinfection by-products, such as trihalomethanes, if chlorine was used as a primary disinfectant?

The primary advantages of POE treatment are economic. For small communities, POE treatment is often cheaper, faster to install, simpler to maintain and operate, and easier to get community support to implement. As communities grow in size, the balance shifts, and centralized treatment typically becomes more attractive.

Point-of-entry water treatment is most often considered by relatively small communities, with less than 40 connections (homes). As a general rule, the smaller the community, the more attractive POE will be from an economic perspective. However, there are rare instances where POE treatment can be an attractive choice for much larger communities. There are a limited number of larger communities in Canada consisting of more than 200 homes that have either installed or strongly considered POE treatment. In B.C., the communities that have implemented POE treatment generally have 15 or fewer connections.

Considering POE to Avoid Chlorination?

One of the most common reasons that POE treatment is so popular with small water systems is the negative perception of centralized treatment involving chlorination. Despite the fact that the chlorination of water is very effective in killing viruses and is one of the greatest public health advances in human history, it has a very negative perception due to the change in taste and smell it creates, as well as concerns that it may be toxic.

These are all valid considerations. However, it should be conveyed to community members that chlorine is very easy to remove once it has disinfected the water and made it safe to consume. There is a very wide array of low-cost filters that can remove the chlorine, ranging from “Brita”-style pitcher filters to whole-house activated carbon filters.

If POE is under consideration as a treatment option solely because of community opposition to chlorination on the basis of these perceptions, it is strongly recommended that community members are informed of the options to remove chlorine from their water. In many cases, some simple education of this fact can go a long way. Performing centralized treatment and then allowing concerned homeowners to remove the chlorine once it reaches their home is perfectly acceptable, and may be much more cost effective.

What are the Components of a Typical POE System?

POE treatment systems typically consist of at least two stages of cartridge filtration, a UV sterilizer, and some ancillary equipment designed to ensure the safe operation of the system.

The first cartridge filter is designed to reduce sediment particles and other physical debris in the water (generally either 5 micron or 1 micron nominal). The second cartridge filter provides filtration to an even finer level (most often to a level of 1 micron absolute). At this level, many waterborne pathogens such as cryptosporidium and giardia, which are commonly found in surface water sources, are removed. These filters meet or exceed the minimum pre-treatment requirements for the UV sterilizer, which is responsible for disinfecting the water to address bacteria, viruses, and other microbiological contaminants.

The ancillary treatment equipment most often includes such things as an emergency solenoid shut-off valve, sample ports, pressure gauges for monitoring filter clogging, a surge protector/back-up power supply, and leak detection devices.

Depending on the contaminants present in the source water, additional treatment may be required to ensure effective operation, to meet the requirements of the Act and Regulations, and to reduce operating costs and maintenance requirements. Additional treatment is generally required when any of the following conditions are present:

  • Turbidity frequently exceeds 3 Nephelometric Turbidity Units (NTU);
  • Hardness exceeds 120 mg/l (7 grains per gallon);
  • Iron exceeds 0.3 mg/l (ppm);
  • Manganese exceeds 0.05 mg/l (ppm);
  • Total Organic Carbon (TOC) is greater than 3 mg/l (ppm) and/or UV Transmittance is less than 80%; or
  • Any other contaminant, other than bacteria indicators, exceeds Health Canada guidelines.

The physical size of a POE system will depend on its specific design. If no additional treatment beyond basic cartridge filtration and a UV sterilizer (and associated ancillary equipment) is required, a residential POE system can be compressed to a size of roughly 40 inches wide, 32 inches tall, and 12 inches deep. Additional space would typically be required above the unit (about 20 inches) for servicing. Of course, if additional treatment equipment is required to address such things as excessive turbidity, hardness, or iron, additional space will be required.

A Caution to Ensure Water Treatment Equipment Meets Requirements

It should be strongly emphasized that not all water treatment equipment is acceptable by the regional health authorities and First Nations Health Authority in the province. There are specific third-party performance and material safety validation requirements that must be met in order for equipment to be approved for use by the relevant Public Health Engineer at the regional health authority or and First Nations Health Authority responsible for your system. For instance, the majority of UV sterilizers on the market do not meet these validation requirements and thus cannot be used. When POE is being contemplated, community members often step forward to indicate that they have already installed their own treatment systems - they should be cautioned that their existing equipment might not meet the health authority requirements.

Where is POE Treatment Equipment Installed?

It is generally recommended that the POE equipment be installed inside the home at the location where the main water line enters the home. This reduces installation costs and provides the highest level of protection to the equipment. In most cases, only a standard electrical outlet is required. Consultation with the homeowner in advance is required to ensure that the equipment is installed in a mutually-acceptable location. Common installation locations include crawl spaces (subject to acceptable height), basements and utility rooms.

The obvious disadvantage of these locations is maintenance access. For this reason, some POE applications have been installed outdoors either in a “box” mounted to the outside of the house, or curbside. This box must be heated and insulated and supplied with power. Outdoor installations, while offering much more convenient access for maintenance, are generally significantly more costly to install.

To reduce the risk of system tampering, some indoor-mounted POE systems have been installed in lockable enclosures.

How Much Does POE Cost?

There are many factors that impact POE cost, including the contaminants in your water, the risks associated with your water system, the amount of work your consultant/ supplier does to assist you in obtaining necessary health authority approvals and permits, the ease of access for installation, the remoteness of your community, etc. If no additional treatment beyond basic cartridge filtration and a UV sterilizer (and associated ancillary equipment) is required, a good preliminary budget number is $3,000 per connection. Costs can vary significantly if additional treatment is required or if exterior installation or a lockable enclosure is desired.

The aforementioned equipment validation requirements can have a material impact on some component costs, particularly for the UV sterilizer. Caution should be exercised when evaluating equipment options to ensure the equipment being considered will meet the necessary health authority guidelines.

To increase cost efficiencies, most POE systems are pre-assembled into a manufactured “panel” in a warehouse or factory environment, rather than assembled at the installation site. This not only improves assembly efficiency and reduces costs, it also enhances standardization across the community, which improves serviceability.

Some Important POE Considerations

100% Participation Required

In order to get approval for POE treatment, it is a requirement of the regional health authorities and the First Nations Health Authority that 100% of the homeowners (and business owners, if applicable) connected to the system agree to the installation of the POE equipment in their homes. The larger a community is, the more difficult it is to achieve full participation. If just one connection does not agree, POE can be very difficult to implement as the termination of a connection may be complicated by political or even legal obligations. Most health authorities require that a letter of consent or similar document be signed by each and every home or business owner indicating their acceptance.

Ownership and Operation Requirements

While exceptions have been granted by certain health authorities, in the vast majority of applications, a key requirement of the health authorities is that POE systems are owned and operated by the water purveyor, not by the individual homeowners. This requirement is intended to ensure standardization of the equipment and that maintenance is undertaken as required by a qualified person. It is far easier and more practical for the health authority to oversee and regulate one water system owner than the many homeowners connected to that system. Accordingly, the water purveyor maintains responsibility for all of the POE systems. To execute its responsibilities for maintenance and monitoring on an ongoing basis, the purveyor needs to be able to access the equipment. This can be unpopular with homeowners and may be a barrier to obtaining community support for a POE project. Fortunately, POE system technology has come a long way, such that access is generally only required once or twice per year.

Depending on the form of governance of the water system, access rights can be entrenched by way of legal service agreements, strata bylaws, etc. In some cases, access rights have been secured by registering a right-of-way on the property titles for lots within the community. In any event, the water system will have to demonstrate to the relevant regulator that it has the authority to access the POE equipment for maintenance and monitoring as required and that it has a policy with some effective consequences for homeowners who fail to comply (e.g., termination of water supply, etc.).

Provisions need to exist so that when a property changes hands, the new owners are made aware of, and are legally bound, by the same requirements as the departing homeowners.

Virus Treatment

B.C.’s health authorities and the First Nations Health Authority require that water be treated, to inactivate 99.99% of pathogenic viruses (4-log reduction). The choice of the specific target virus for this reduction goal has important implications for the choice of treatment equipment. Some of the health authorities use Rotavirus as their target, which can be inactivated to the required 99.99% level using a UV sterilizer validated to a minimum UV dose of 40 mJ/cm2. UV sterilizers that are validated to NSF/ANSI Standard 55 Class A are certified to meet this dosage requirement and are therefore the most common choice for point-of-entry systems. UV sterilizers that do not have this validation cannot generally be used in POE applications in B.C. It should be noted that UV sterilizers that are certified to NSF/ANSI Standard 55 Class B are NOT acceptable, as they are only validated to a dose of 16 mJ/cm2, and they lack many of the important safety features found in Class A devices.

Some health authorities use Adenovirus as their target virus for 4-log inactivation. Adenovirus is much more resistant to UV disinfection and requires a dose of 186 mJ/cm2 for 99.99% inactivation. Affordable UV equipment validated to this UV dose is very limited but is available. As you might expect, it is considerably more expensive. Many health authorities that apply the Adenorvirus target allow for the use of NSF/ANSI Standard 55 Class A validated UV sterilizers in POE applications, as a risk reduction strategy (while acknowledging that the 4-log virus reduction requirement is not fully met). This is most common in applications deemed to be at low risk of contamination from human waste. Such an exception is only granted at the health authority’s discretion.

Operator Training

Generally speaking, POE treatments systems require less sophisticated operators, as compared to centralized systems. While contractors can be hired to take care of all maintenance, it is possible for community volunteers to be trained in general maintenance tasks. This can reduce ongoing operating costs.

Where Do You Start?

Of course, before the selection of a treatment approach can begin, communities need to ensure that they have an effective governance structure in place, with representatives who are duly authorized to act on behalf of the community when negotiating with suppliers, applying for funding (if applicable), submitting applications for construction permits, and working on ongoing compliance issues with regulators. An effective governance structure provides confidence to regulators. Systems that have gained the confidence of regulators are more likely to be granted exemptions and exceptions that will keep costs down and generally make the permitting process smoother and faster.

Once governance is in place, it is imperative that the community begin to involve its citizens in the process of choosing a water treatment solution. Every opportunity should be taken to educate community members of the importance of meeting the requirements of the Act and Regulations and the options available to meet treatment obligations. Myths and misinformation should be quickly dispelled. Through positive education, a remarkable turn-around in the acceptance of the need for water treatment can be achieved, even among those most opposed to any form of treatment. Involving community members will give them the opportunity to provide constructive input into the protection of their most valuable resource.

Similarly, establishing an open dialogue with health authority officials [NOTE1] early in the process will create a co-operative framework that will positively influence the future approval of the community’s preferred treatment option as well as the negotiation of installation and ongoing compliance monitoring requirements. Early involvement of the Drinking Water Officer from the local health authority will give you indications of their requirements and concerns about POE treatment as it would apply to your system so you are aware of potential obstacles that you will need to plan to overcome in your proposal.

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