Decentralized: Point of Entry Systems

For small communities, POE treatment can be cheaper, simpler to operate, and easier to get community support to implement. However, regular maintenance is essential for these devices to operate effectively and provide safe drinking water. 

As communities grow in size, the balance shifts, and centralized treatment typically becomes more attractive. 

Considering POE and Importance of Chlorination

One of the most common reasons that POE treatment is considered by small water systems is that centralized treatment is often associated with chlorination. There is a negative perception due to the change in taste and smell chlorine creates, as well as concerns that it may be toxic. Chlorination of water is very effective in killing microorganisms, therefore it is essential for deactivation of some pathogens and provides a chlorine residual in the distribution system, which creates secondary disinfection.

Removal of disinfection by-product precursors by treatment and filtration is important because studies have shown a link between long-term exposure to high levels of chlorination by-products and an increased risk of cancer. Chlorine disinfection by-products (DBPs) include: trihalomethanes (THMs) and haloacetic acids (HAAs). Health Canada has established a Maximum Acceptable Concentration (MAC) for THMs and for HAAs as set out in the Guidelines for Canadian Drinking Water Quality. The cancer risk at concentrations below the MACs over a lifetime is considered extremely low. 

The health (cancer risk) and aesthetic (taste and odour) concerns associated with chlorinated water are valid concerns. However, these concerns can be managed by regularly testing the DBPs at the ends of the distribution system and by educating the water users about the benefits of chlorine and the methods for removing the chlorine after the water has been disinfected. Activated carbon filters (installed in a water pitcher or on a faucet) can be used to remove chlorine and its by-products. It is essential to follow the manufacturer’s instructions when using such a filter.

If POE is under consideration as a treatment option solely because of community opposition to chlorination, it is strongly recommended that community members are informed of the options to remove chlorine from their water. Performing centralized treatment and then allowing concerned homeowners to remove the chlorine (through the use of special filters) once it reaches their home is perfectly acceptable, and may be much more cost effective.

Components of a Typical POE System

POE treatment systems typically consist of at least two stages of cartridge filtration, an ultraviolet (UV) light radiation disinfection unit, and some ancillary equipment designed to ensure the safe operation of the system. The manufacturers often refer to the UV lamps as “sterilizers” but they don’t actually sterilize the water as they don’t eliminate all viable forms of life such as bacterial spores and prions. 

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

Treatment equipment must include supporting items such as an emergency solenoid shut-off valve, sample ports, pressure gauges for monitoring filter clogging, a surge protector/back-up power supply, a built-in flow restrictor or automatic fixed flow rate control 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 DWPA and DWPR, and to reduce operating costs and maintenance requirements. For more information on Ultraviolet (UV) light radiation disinfection and the recommended water quality entering a UV reactor, refer to the Online Help Centre’s web page:  Common Water Disinfectants and How to Select Them.

The physical size of a POE system will depend on its specific design and the minimum flow rate to serve a given population. If no additional treatment is required beyond basic cartridge filtration and a UV lamp disinfection unit (and associated equipment), a residential POE system can be compressed to a size of roughly 40 inches wide, 32 inches tall, and 12 inches deep (100 cm x 80 cm x 30 cm). Additional space would typically be required above the unit (about 20 inches or 50 cm) for servicing and lamp replacement. If additional treatment equipment is required to address such things as excessive turbidity, hardness, or iron, additional space will be required.

Ensuring Water Treatment Equipment Meets Requirements

Not all water treatment equipment is acceptable to the regional health authorities and First Nations Health Authority (FNHA) 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 FNHA responsible for your system. 

For instance, the majority of UV lamp disinfection units on the market do not meet these validation requirements and cannot be used. When POE is being contemplated, community members often step forward to indicate that they have already installed their own treatment systems; however they should be cautioned that their existing equipment might not meet the health authority requirements.

Installation of POE Treatment Equipment

Generally, POE equipment should be installed inside the home at the location where the primary service line enters the home. In most cases, only a standard electrical outlet is required. The homeowner should be consulted 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 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.

Cost of POE

There are many factors that impact POE cost, including the contaminants in your water (i.e. the raw water quality), the risks associated with your water system, the amount of work your consultant/supplier does to assist you in obtaining the 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 disinfection unit (and associated ancillary equipment) is required, a good preliminary budget number is about $5,000 to $8,000 per connection (the more connections the lower the cost due to the economy of scale). Costs can vary significantly if additional treatment is required or if exterior installation or a lockable enclosure is desired.

Equipment validation requirements can impact component costs, particularly for the UV unit. When evaluating equipment options, ensure the equipment being considered will meet the necessary health authority guidelines.

For cost efficiency, most POE systems are pre-assembled into a manufactured “panel” in a warehouse or factory, rather than assembled at the installation site. This reduces costs, and creates standardization across the community, which improves serviceability.

Exemptions and Obligations

The exemption for “small systems” from supplying potable water to the homes/businesses if they have POE/POU units that produce potable water does not apply to the regulations made under the DWPA or to all of the requirements on the water supplier’s operating permit. It only exempts the water in the distribution system from the source up to the point of connection with a POE/POU device from:

• meeting the requirement of being potable
• meeting any additional requirements established by the regulations or by the system’s operating permit related to water quality. 

This exemption no longer applies once the water enters the treatment device as the exemption is contingent on there being a POE/POU device that “makes the water potable”. All water exiting the POE/POU unit must meet the requirements laid out by the DWPA, DWPR, and your local Drinking Water Officer.

Ownership and Operational Requirements 

For most systems, a key requirement of the health authorities is that POE systems are owned and operated by the water purveyor/supplier, not by the individual homeowners. While exceptions have been granted by certain health authorities, this requirement is intended to ensure standardization of the equipment and that maintenance is undertaken as required by a qualified person. 

Access Agreements

In order to maintain and monitor the POE/POU equipment, access to the equipment is required. This can be unpopular with homeowners and may be a barrier to obtaining community support for a POE project. Fortunately, access is generally only required a few times 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 land titles of lots within the community. As the water supplier, you will need to prove to the regulator that you can access the POE equipment for maintenance and monitoring as required. You may want to have a policy requiring homeowners to grant access to the treatment equipment with effective consequences for homeowners who fail to allow access (e.g., termination of water supply, etc.).

These 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. Before the property is sold, information regarding the POE treatment system and the required water supplier access should be disclosed to the prospective purchaser.

100% Participation and Consent Required

In order to get approval for POE treatment, it is a requirement of the regional health authorities and the FNHA 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 and understanding of what a POE entails.

Construction Permits for POE/POU Treatment Equipment

You must apply for and obtain a Construction Permit (CP) for the chosen POE/POU treatment equipment that will be installed in the homes and businesses you are providing water to. You must apply to the regional health authority for this. Assuming your application is successful, they will issue a CP which gives the water supplier permission to install the POE/POU treatment equipment. 

General Operation and Maintenance Requirements

Each home and business must have the same POE/POU treatment equipment as specified in the Construction Permit (CP). Having identical equipment makes servicing and maintenance easier, and a reserve of spare parts should be maintained. To ensure that the end users receive potable water, the water supplier must do the follow for each POE/POU unit:

• monitor the treated water quality (primarily bacteriological sampling unless treatment has been provided for chemical contaminants) on a regular basis (samples from each POE/POU unit are usually collected on a scheduled rotating basis)
• check and maintain the POE/POU units such that they are kept in good working condition (using maintenance schedules, etc.)

• Regulators will usually require a water quality monitoring plan to verify that these devices are working properly.

As well, the bacteriological quality of the raw untreated source water must be monitored at least quarterly to capture seasonal variations. The chemical quality of the raw water being supplied to the residences/businesses should be monitored at least every 3 to 5 years, as recommended for all water supply systems.

Virus Treatment

BC’s regional health authorities and the FNHA require that water be treated to provide a 4-log (99.99%) reduction or inactivation of pathogenic enteric viruses. The choice of the specific target virus for this reduction goal has important implications for the choice of treatment equipment.

Adenovirus and Rotavirus are types of enteric viruses that are excreted in the faeces of infected humans (i.e. they are found in sewage effluent). These viruses present a risk to water sources that may be susceptible to contamination from sewage 

Health authorities use Adenovirus as their target virus for 4-log inactivation of viruses. 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 Adenovirus 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).

Chlorination meeting the appropriate CT disinfection factor will provide a 4-log inactivation of Adenovirus.

 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.

For more information about enteric viruses and their inactivation, refer to the section entitled “Pathogen Log Reduction Credits for Protozoans and Viruses” under “Ultraviolet (UV) Light Radiation” at the Online Help Centre’s web page Common Water Disinfectants and How to Choose Them.

Starting the POE/POU Treatment Process for your Small Water System

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. The authorized representatives will need to:

• negotiate with suppliers
• apply for funding to senior governments (if applicable for the specific governance structure)
• submit applications for Construction Permits to the regional Public Health Engineer (PHE)
• work with regulators regarding ongoing compliance issues

An effective governance structure gives regulators confidence in your system, which means you are more likely to be granted exemptions and exceptions that will keep costs down and generally make the permitting process smoother and faster.

Next, you can begin to involve citizens in the process of choosing a water treatment solution. It is your responsibility to inform citizens about the importance of meeting the requirements of the BC drinking water legislation (the DWPA and the DWPR) and the options available to meet treatment obligations (i.e. centralized treatment or decentralized treatment involving POE and/or POU treatment).

The consequences of no action (no approved treatment method):

• everyone will continue to be exposed to the health risks of drinking non-potable water
• the health authority will keep the water system on a water advisory until approved treatment is provided
• property values may decrease due to the unsafe water and lack of compliance 
• home insurance may increase because of the lack of compliance

Providing positive education based on facts can often shift a community from opposition to treatment to support for treatment. Involving community members will give them the opportunity to provide constructive input into the protection of their most valuable resource.

Establish an open dialogue with health authority officials early in the process to create a co-operative and positive working relationship. This will help when the community is looking for approval of their preferred treatment option and when confronted with ongoing compliance issues. Early involvement of the health authority’s local Drinking Water Officer (DWO) will help you sort out the pros and cons of POE treatment as it applies to your water system. The DWO will also outline the possible benefits, the legislative requirements and the potential obstacles that would need to be addressed before you decide on moving forward with POE/POU treatment.

Alternatives to Decentralized Treatment

Small water systems may use Centralized Water Treatment Systems. There are advantages and disadvantages to both treatment options, which you can find outlined on our page Centralized vs Decentralized Water Treatment Systems.