No piece of water treatment equipment will operate indefinitely. All will require periodic maintenance and inspection to ensure proper treatment is taking place. The maintenance intervals will vary with the type of treatment involved, the inlet water quality and water usage. As in Learning Task 4, this chapter will target softeners, iron filters, reverse osmosis units and UV sterilizers, as these are the most common pieces in use for residential water treatment. For safety’s sake, remember to isolate the piece of treatment equipment, both power-and-water-wise, before disassembling any unit. Lock out or tag out equipment as necessary.

Media Filters

Whole-house filters fall into several categories, which treat problems in water such as:

• Taste and odor
• Chloramine removal
• Suspended solids (silt and sediment)
• Acidity

The media in the tanks that treat taste and odor, chloramines, and suspended solids will generally not be consumed so will not need replacement for many years. On the other hand, acid filters contain base (alkaline) elements that dissolve as they neutralize the acid in the water. Therefore, acid neutralizers will require periodic replacement of the media. Limestone chips, also known as calcium carbonate or calcite, have typically been the common material for acid neutralizers. Always use the product that is recommended by the manufacturer. To check the level of calcite in the tank, shine a flashlight up against the back of the tank. The level of calcite should be visible through the opaque fiberglass. Consult manufacturers’ literature for recommended media levels. To add calcite, available in bags of approximately 50 pounds (22.7 kgs) first put the neutralizer onto bypass. Next loosen and undo the union fittings between the control head and bypass valves. Expect some water to escape the piping and have rags on hand to contain the drips. Then remove the control head by unscrewing it counterclockwise from the tank. Carefully wiggle the control head upward and clear of the tank, ensuring the distributor tube stays in place in the tank. Block the top of the tube using tape or a pipe cap so that no calcite drops into it during the calcite refilling process. Next, siphon some of the water out of the tank, to create space for the fresh calcite. Inspect, clean, and reinstall the removeable strainer that is attached to the underside of the control head, as well as the end of the distributor pipe before plugging or capping it. Always be sure to lubricate any O-rings using manufacturer-recommended lubricants or silicone-based lubricant. Using either a makeshift funnel or one specific for the purpose, with the distributor pipe end capped off, pour the required amount of calcite from the bag into the tank until it reaches the level recommended by the manufacturer. The level should be able to be seen and measured through the tank opening as well as via the flashlight method. Remove the cap from the distributor pipe and lubricate the tank seal O-ring and any O-ring sealing the distributor pipe to the control head. Carefully align and introduce the distributor pipe into the control head and tighten the control head back onto the tank. Refasten the bypass to the control head and slowly open the incoming water valve to pressurize the neutralizer. Check for leaks, then slowly open the outlet valve. Trapped air should escape the tank into the piping and be bled off at the faucets. Remove faucet aerators when bleeding off in case any calcite is carried out of the tank in the initial filling process.

Softeners

To retain the appearance of a new water softener, occasionally clean it with a mild soap solution. Do NOT use abrasive cleaners, ammonia, or solvents, and take care to not allow any cleaning solution to get inside the control head.

The maintenance of the interior components of a water softener is largely dependent upon the specific manufacturer’s recommendations. The seals and spacers along with the piston assembly should be inspected/cleaned or replaced annually or as required depending on the inlet water quality and water usage.

If the inlet water to the softener contains iron, even in small amounts, the resin could become clogged in a short period of time, necessitating resin replacement. To avoid this problem, an approved resin cleaner must be used. Bottled solutions such as RESCARE® are available and attach easily to the inside of the brine tank. The solution is automatically dispensed through a wick into the brine solution where it helps to clean the resin during the regeneration cycle. The most important consideration when using a resin cleaner is to make sure the solution bottle is never empty. The media inside the tank should give many years of trouble-free operation, but if salt is being consumed at its regular rate without the water being softened, it is an indication that the media bed is needing to be replaced. When media replacement is required, manufacturers will specify the type and amounts of media needed for each model of softener and will also provide instruction on proper replacement. The process is similar to that of adding calcite to an acid neutralizer, with the exception that all the contents must be removed and replaced. Once the head is removed, softener tank is inverted and, using a garden hose, the contents are rinsed away. New layers of coarse gravel, fine gravel and media will be poured in around the distributor tube. The head is reinstalled, and the softener is put through the same procedures as when it was initially started.

The control head contains piston assemblies, seals and spacers that may require maintenance. The manufacturer’s literature will contain instructions and exploded-view diagrams specific to each model, to allow service or replacement of malfunctioning components. Make sure to follow manufacturers’ instructions to the letter, which include the use of silicone lubricant, rather than petroleum-based grease, on seals and O-rings.

Probably the most common repair to the control head involves the cleaning of the brine injector. Sediment, salt, and silt are the common culprits for clogging injectors, which can result in an excessive water level in the brine tank. Fortunately, most manufacturers recognize that this component may require frequent service, so they locate it on the side of the control head where access is relatively easy. To clean the injector, the injector cover is removed, and the injector can be carefully pulled from the injector body. Encrustations of salt can first be removed by mechanically breaking them off using a small implement such as a small screwdriver, wire, or paper clip, and then immersing the injector in a mild acid such as vinegar to clean out the small holes in the orifice and throat. Reassembly is the reverse of disassembly, using silicone lubricant on any seals or O-rings.

Brine tank maintenance involves two main considerations, which are maintaining a salt level in the tank and ensuring the salt doesn’t “bridge”. Bridging is the term used when water has dissolved the salt below the observed top of the salt heap, leaving a void below. 80 to 100 pounds (36 to 45 kgs) of clean salt labeled for water softener use, in the form of crystals, nuggets, pellets or buttons, is initially added to the brine tank on startup. Thereafter, make sure the salt level is always above the level of the brine solution. The use of natural rock salt is discouraged because it contains insoluble silt and sand which build up in the brine tank and causes problems with the system’s operation. To prevent bridging, whenever checking the salt level, use a clean stick to poke through the top of the salt heap which will knock down any compacted bridges. Alternately, pour warm water down the inside walls of the tank or gently tap against the outside of the tank with a rubber mallet, being careful to not break the plastic.

Brine tanks will build up a layer of sludge (undissolved salt) that will increase over time, so every 2 – 3 years the tank should be cleaned out and restarted using the initial startup procedures.

Too much or not enough salt being used can be an indication that the initial settings of the control head should be re-examined. Before assuming that a component is malfunctioning, check the settings and make sure the hardness value is compensated for any iron or manganese detected in the water supply. As well, the number of people in the house could have changed over time, which will affect regeneration intervals.

Manganese Greensand Iron Filters

Iron filters that use greensand as the media bed operate in much the same manner as a softener. The greensand filter media oxidizes dissolved iron and manganese on contact as the water flows through the filter media. These elements precipitate (form solids) in the bed of the filter, and the regeneration process backwashes these small particles to drain every few days, thereby cleaning and restoring the filter media. Most problems occur when the permanganate solution is not being drawn into the filter during each backwash cycle. To check this operation, disconnect the brine tank tubing at the control valve and consult the operation manual to initiate a brine cycle. A fairly strong vacuum should be felt at the brine tube inlet port of the control head. If not sensed, the injector inside the head is likely plugged and must be cleaned. If there is vacuum there, check the brine tank float for obstructions or the possibility of a rubber band, installed for shipping purposes, still in place around the float. If there is vacuum there, but no permanganate solution is being drawn in, the float assembly must be cleaned or replaced.

It is also important to check and maintain the incoming water’s pH level to between 6.7 and 8.8. An acid neutralizing filter, installed on the upstream side of the greensand filter, may be needed to achieve these levels.

Dripping at the drain pipe opening when the unit is in the “service” cycle is an indication that there is an issue with the control valve. The control head valve contains pistons and O-rings that may need periodic cleaning, lubrication, or replacement. Manufacturers’ literature contains exploded parts diagrams and will detail the steps required to enable routine maintenance of the control head. These steps are usually simple enough that homeowners, using basic tools, will be able to perform them. Be sure to have the specific literature on hand before attempting to disassemble any control head.

Pink water out of the home’s faucets indicate that potassium permanganate residue is being carried through the system. The control head’s settings should be adjusted to provide adequate backwash and rinse cycles, provided that the flow rate through the unit is sufficient. To achieve proper flow rates, most manufacturers recommend a minimum of 30 psi (210 kPa) at the filter’s inlet and suggest that a minimum of 40–50 psi (280-350 kPa) works best.

Sometimes if the brine tank is not filling adequately, it is possible that the float assembly in

the tank is set too low. The float should be several inches above the air check valve inside the tank. This will allow for enough water to be added to the tank before shutting the brine fill cycle. If necessary, pull the float assembly rod up to the appropriate height, and cut the rod at that height while keeping the rubber washers positioned with adequate space to hold the float in place.

The level of potassium permanganate in the “brine” tank should be checked periodically and maintained to manufacturers’ recommendations. Manufacturers suggest 5 pounds (2.3 kg) of dry potassium permanganate powder be added to the tank every two or three months to maintain an acceptable level. Greensand replacement interval is generally every 4 – 6 years. Follow specific manufacturers’ instructions to do so.

Chemical-Free Iron Filters

Chemical-free iron filters do not use a regenerating agent such as salt or potassium permanganate. Instead, they rely on the oxidation of clear water iron (ferrous) and red water iron (ferric) into particles of rust that can be trapped by the special media inside the tank and backwashed to a drain. For the special media to work efficiently, the incoming water must be within certain parameters, which are:

• pH of 7.0 to 8.5 or 6.0 to 6.9 (depending on model chosen)
• Iron concentration maximum of 30.0 ppm
• H2S maximum of 5.0 ppm
• Manganese of 0.0 to 1.0 ppm (depending on model chosen)
• Minimum 20 psi (140 kPa) inlet water pressure

If low pH incoming water is encountered, a neutralizing filter should be installed upstream of the chem-free iron filter, or alternately a variety of chem-free iron filter that contains a neutralizing media bed can be used. If so, the media bed will be dissolved over time and will need periodic replacement. A routine water analysis on both upstream and downstream water samples will provide information indicating any change in water quality that may necessitate service or repair.

Although the chem-free iron filters use no regenerating agent, the control head valves still require periodic service, and their disassembly follows the same general procedures as the softeners and greensand filters. Always make sure to use proper PPE and remove both power and water pressure to the unit before working on it and to follow manufacturers’ specific instructions.

Air injector assemblies of chem-free iron filters require periodic inspection and service, and like the brine injectors on softeners and greensand filters, are easy to access, usually located on the side of the control head. They can be disassembled, cleaned, and reinstalled relatively easily without the use of special tools.

Any red colour either in the water when drawn or left as stains on fixtures indicates that the chem-free filter is not doing its job and needs to be serviced. Insufficient air draw and/or improper backwashing cycles are the most common culprits for these issues. The air injector should be serviced, and the programming should be checked to ensure proper cycling of the filter, particularly the length of the backwash cycle.

If excessive pressure loss through the filter is experienced, the media bed may have become compacted due to excessive buildup of precipitated iron and will need to be broken up by removing the control head and manually stirring with a stick or pipe. The control should then be reprogrammed to backwash at more frequent intervals to avoid recurrence.

Reverse Osmosis Units

Routine maintenance RO system is fairly straightforward, in that there are only three main components to the system, which are the faucet, cartridge bank, and pressure tank.

RO faucet (spigot) – This component normally needs no regular maintenance. The swivel gooseneck should move freely and, if not, may need the O-ring seal to be lubricated or replaced. If the trigger or handle controlling the flow leaks, dismantle it and lubricate or replace the seals (if possible), otherwise replace the spout.

Cartridge bank – RO units have either 3 or 4 cartridges. Those with 3 cartridges have, in order of flow, a sediment filter, membrane, and carbon filter; the 4-cartridge variety have two carbon filters, one upstream of the membrane (called a carbon block filter) and the other downstream of it (called a polishing or post GAC filter). The following are the replacement intervals suggested by most manufacturers, with a note that incoming water quality and amount of usage can necessitate more frequent replacement.

• Sediment filter – every 12 months
• Carbon block filter – every 6 to 12 months
• RO membrane – every 2 to 5 years
• Granular activated carbon (GAC) filter – every 6 to 12 months

Because 12 months is an interval common to the carbon and sediment filters, that is the usual replacement interval for them. Most public water supplies are chlorinated, and chlorine will harm the RO membrane, so the presence and regular replacement of the carbon block filter is critical to the life of the RO membrane used on a public water supply.

Cartridges are of a push-and-turn type, with O-rings mounted on the cartridge stem to provide the seal. Replacement usually involves shutting off the water supplies to both the unit and from the pressure tank and opening the faucet to relieve any pressure in the cartridge bank. With a shallow pan under the assembly to catch any drips, the cartridges can then be removed and replaced. Follow the specific manufacturer’s instructions for flushing the system after replacement, as each cartridge will have different requirements for flushing.

Pressure tank – The pressure tank operates similarly to one in a well pump system. It has a bladder that separates the air in it from the product water. Check the air pressure in the tank when there is a noticeable decrease in the available water from the RO system. To do this, the tank must first be emptied of water by shutting off the water supply to the unit and opening the RO faucet. When the flow of water from the faucet has slowed to a trickle or stopped, check the air pressure at the Schrader valve and adjust it to the manufacturer’s specifications, usually from 6 to 10 psi (42 to 70 kPa) using a tire pump or oil-free compressor and a low-pressure tire gauge. If the tank is visually leaking or requires frequent topping up, it is an indication that the tank should be replaced. Follow the specific manufacturer’s instructions for flushing the tank and system after tank replacement.

Sanitizing an RO System

Eventually, an RO system will accumulate slime and other deposits and will require cleaning and sanitization. Most manufacturers suggest sanitizing RO systems annually, coincidental with cartridge replacement. The manufacturer’s instructions should be followed but in their absence, the following are recognized as appropriate steps.

• If sanitizing the system when new filters will be installed, all new filters should remain in the original packaging until it is time for replacement.
• The service area should be free of any excess dirt or dust
• Wash hands with soap and water, and/or wear sanitary gloves
• Shut off the main valve completely, and dispense all of the water from the RO faucet
• Remove the existing membrane and filters from their housings and screw the empty housings back into place
• Pour about 1 cup of hydrogen peroxide into the housing furthest upstream
• Turn the main valve back on and allow the system to run (without the filters, the storage tank will refill rapidly) until no water flow can be heard
• Turn off the main valve and turn on the RO faucet, let run until the water flow stops
• Turn off the RO faucet and turn on the main valve, again wait until no more water flow is heard.
• Repeat the last two steps one more time, then shut off the main valve again and install the new filters
• Turn the main valve on, let the tank fill back up and then perform one more fill and drain sequence

Some manufacturers suggest exhausting at least three tanks of water before drinking from it. If the RO unit supplies an ice maker, always shut off the supply to the ice maker before any cartridge replacements or sanitization is done and discard the first two trays of ice after being put back into operation.

Arsenic,Chlorine and RO Systems

As mentioned in Learning Task 1, RO systems are very effective at removing pentavalent arsenic, bringing the content down to within government standards for drinking water, but they will not convert trivalent arsenic to pentavalent arsenic. A free chlorine residual in the water supply will rapidly convert trivalent arsenic to pentavalent arsenic, as will other water treatment chemicals such as ozone and potassium permanganate. A combined chlorine residual, called chloramine, in a water supply may not convert all the trivalent arsenic into pentavalent arsenic. If a water supply is from a public water utility, contact the utility to find out if free chlorine or combined chlorine is used in the water system. This is important for two reasons, the first being the effect that chlorine will have on the RO membrane, likely requiring a carbon block filter upstream of the membrane and/or more frequent membrane replacement. The second is the possibility of small amounts of trivalent arsenic being present in the water supply. Based upon field testing, one manufacturer has determined that their RO units are capable of removing up to 2/3 of trivalent arsenic from drinking water, provided the RO membrane is maintained according to its recommended maintenance cycle. Frequent testing of the incoming and product water may be necessary to ensure the health and well being of the household occupants.

UV Sterilizers

The inside of the quartz-glass sleeve should be cleaned every 6 months with a mild solution of soap and water, and dried before reinstalling. Poor water quality or the presence of iron will necessitate more frequent cleaning. Use only an approved silicone-based lubricant on O-rings and seals. The 5-micron filtering system upstream of the UV unit must be maintained to ensure the effectiveness of the UV system.

Although UV lamps will last longer than a year (usually 9000 hours), their effectiveness diminishes with time. Therefore, they are expected to be replaced annually. Some manufacturers provide a countdown timer, set for 365 days, to ensure the owner is reminded of the replacement interval. Once the lamp has been replaced, the timer must be reset. The timer is not an integral component to the UV assembly and can be mounted anywhere that it’s notification “beep” can be heard. Although the battery inside the timer generally lasts for years, it’s a good idea and of relatively little cost to replace it coincidently with the lamp.

Remember that the UV sterilizer is there due to possibly harmful microorganisms in the water supply, therefore, when any service is done to the UV unit, it is imperative that the water not be used for drinking until the system has been sanitized and the UV unit is back online.

Now complete Self-Test 8 and check your answers.

Self-Test 8