• September 08, 2022 6 min read

    Do Water Softeners Need A Drain?

    do water softeners need a drain

    A water softener is the appliance that removes minerals from water. For more about water softeners and how they work, please see the Water Softeners Buying Guide. Here we’ll look at where and how to install one.

    If you’re asking yourself, “where does a water softener go?”, it’s time to do a bit of investigating around your home. On the other hand, if you have a general understanding of how to plumb a water softener, you can quickly identify the most effective location.

    If you’re installing a whole-home system, you’re going to want to place the softener as close to the entry point for water in your home. As a general rule, it’s best to place a water softener at the earliest possible point in your home plumbing system. That means placing your water softener somewhere it can feed into your water heater, rather than placing it downstream from this equipment. Not only will you prevent hot water from damaging your softener, but you will also extend the life of your water heater by feeding it softer water.

    For starters, a new water softener should be located out of the way but where it is easy to tie it into the plumbing system—in most cases, this is in a basement, garage, or utility room, often near the water heater. Allow enough space around the equipment for easy servicing. A water softener will need a drain such as a floor drain or utility sink.  Most water softeners require two drain tubes. One of the drain tubes connects to the control valve and is used to void the backwash water during the regeneration cycle. The other drain tube connects to the brine tank and serves as an overflow drain. Both lines then run to the home drain, but they should not be connected together.

    A laundry sink or any other sink can serve satisfactorily as an emptying place for the drain line, but it’s always best to discharge to the sewer whenever possible.

    A trap installed in a waste line will also suffice, providing there is a proper air gap or vacuum breaker between the tap and the drain line from the softener.

    A funnel arrangement may also be advantageously used in such an installation. A floor drain may also be used if it is out of the way of traffic. Rigid pipe should be used and positioned so that the minimum air gap cannot be reduced by moving the pipe. When the water treatment system is supplied with flexible drain line material, the drain must be tightly secured in the correct position to avoid deliberate or accidental movement.

    Some units provide an overflow drain line for the regenerant container. Such a line should be run to a floor drain. It must run by gravity feed to a lower drain.

    Are water softeners really necessary?

    water flowing from pipe

    Most likely if your asking this question, you're in the midst of a water softener installation !

    One of the most important components of a proper softener installation is provision for safe drainage by avoiding a possible “cross connection”. A cross connection is any point at which a water supply pipe or container is joined directly to a sewer pipe. It is at this point alone that it is even remotely possible for a water softening/conditioning system to introduce a hazard to a household. This can not happen if safe drainage is provided by using a sufficient air gap in the installation. NEVER MAKE A CROSS CONNECTION.

    There are very simple reasons why a water treatment system must never be connected directly to a sewer pipe:

    Consider a water treatment system installed with a direct drain connection to the sewer system, that is a cross connection. If, during the regeneration cycle there is a fire in the vicinity. What would happen if the firemen’s pumping equipment creates such a strong demand for water that suction occurs and it actually causes water to flow from the house back into the main line? Actually, if the suction were strong enough, some fluid from sewer pipes might be drawn back through the water treatment system and back out into the water supply lines. The danger is that sewage containing potentially pathogenic organisms could then be introduced into the water supply.

    Obviously, the public health and the private welfare of your household must be at the uppermost consideration in the mind of the installer at all times. This is why the air gap rule must always be followed for drainage installations.

    A softener drain line must not be connected directly to the waste system, but must be emptied into a laundry tray, floor drain, or properly trapped special outlet, preserving an air gap of at least two times the diameter of the drain line, but in no case less than 1-1/2″ above the top of the receptacle used. The greater of two and a half times the diameter of the equipment’s indirect drain or 1-1/2″ is the minimum air gap for whole house (point-of-entry) water treatment equipment. The greater of 2.5 times the equipment effective drain line diameter, or one inch, is allowed for point-of-use equipment. In addition, the end of the drain line should be secured so that there is no chance that it can become immersed in waste fluids.

    Be sure to study and follow the equipment manufacturer’s installation instructions. They will specify drain line size. If the proper size is not provided, the unit may not be properly backwashed.

    Why Your Water Softener Needs a Drain

    Water softeners remove hard water minerals, and to some degree, they also remove small amounts of dirt and debris from your water.

    The hard minerals stick to little plastic resin beads, and the dirt settles and collects at the bottom of the tank.

    After so many gallons have been treated, the softener needs to clean itself out, aka regenerate.

    The softener uses salt to remove the hard mineral deposits built up inside the system.

    But what about all that crud in the bottom of the tank?

    This is where the softener drain line comes into play – You need a POWERFUL flush to get it out!

    What Happens if the Softener Drain Line is Blocked?

    If you were watering a plant, and someone steps on the hose you are using, what would happen?

    The plant wouldn’t get much water.

    Now think about your water softener. You need to flush out all the crud you’ve collected in the tank, but the drain line has collapsed. What was once a ½” line, is now ⅛”.

    Over time, dirt and excess hardness and iron will begin to plug up your water softener resin. Once damaged, resin is very expensive to replace, and you end up with a huge water softener repair bill.

    If a drain line becomes severely restricted, it can actually blow off the softener during regeneration and cause a massive flood!

    The drain hose that comes from the water softener needs to terminate in a manner that won't create a potential cross-connection between the potable water and anything else... such as sewer water. This is usually achieved with an air gap; this is just a literal gap between the end of the discharge pipe and the drain receptor, whether it's a floor drain, standpipe, or laundry sink. The only problem with the diagram below, which is what one of the water softener manufacturers includes in their installation manual, is that water will shoot all over the place. When water softeners discharge water, the water flows fast. It doesn't dribble out.


    Where should a water softener drain line be?

    There are various options to accomplish drain requirements. Often, the drain lines are run to a floor drain, but you can also extend the drain line into the standpipe that also drains a washing machine, or into a utility sink or sump pit.

    In most communities, it is illegal to connect the water softener drain directly to the home drain system without an air gap. Similar to the requirement for dishwashers, the drain line needs an air gap fitting designed to prevent back-siphoning of contaminated drain water into the water softener. There are special air gap fittings that allow you to connect the water softener's drain tubes directly to a drainpipe or standpipe.

    In our example, the owner has installed a dedicated drain pipe with a trap, into which they have run the two drain tubes for the water softener. A slight separation between the drain tubes and the drain pipe provides the required air gap.

    To connect the drain tubes, attach a length of 1/2-inch (inside diameter) flexible tubing to the drain elbows on both the control valve and the brine tank, using hose clamps, and run the tubes to the selected drain location. Attach them to an air gap fitting if you are using one, or anchor them securely to a utility sink or floor drain.