This is the perfect question for window cleaners.
There is no straight answer. There are many variables. Some are within your control, and others are out of your hands.
Deionizing resin, a consumable part, is used in Window Cleaning systems to purify the water. You can use it as part of a 4-stage RO/DI filtration or as a standalone means to purify your water. (For more information, see our article Types of Filtration, RO/DI Only).
Many variables will affect how long your resin can last before it stops purifying water enough. However, some major factors will impact its longevity.
Dimension of the DI vessel (volume resin)
Simply put, the larger the vessel, you will need less resin to change. There are many sizes to choose from, including the 11L and 25L sizes. The 11 Litre will require replacement more frequently, while a 25L bag will give you two full refills. HydroPower is a long-lasting vessel that distributes water evenly through the resin. This increases the amount of water you can make from the same volume.
Total dissolved solids from the input water
Tap water can be classified as either hard or soft. However, it isn’t quite as simple as that. The UK tap water TDS readings range between 30ppm and 500ppm (parts/million). Knowing where you are on this scale will indicate how long you can expect your window cleaning resin to last. A TDS Meter can take a reading from your tap. This will allow you to determine the type of filter you should use. We recommend that water below 150ppm be considered soft water, and anything higher is considered hard water. A soft water area can last for several months before resin changes occur. Hard water, however, can take as little as a few days to pass resin.
Water usage per day
Your water purification rate is the last thing that will affect the life of the resin. A system that uses 650 Litres of water per day will need to be changed more frequently than one operator who uses only 300 litres.
Trial and error is the only way to determine the life expectancy of your resin. You will need to track how much water you drink each day and what size filter system you are using. This won’t give you an exact length as the TDS readings in tap water can change over time. You will also notice changes between seasons. It is important to keep track of the resin’s lifespan to help the budget.