Water dispenser


A water dispenser, sometimes referred to as a water cooler, is a machine that dispenses and often also cools or heats up water with a refrigeration unit. It is commonly located near the restroom due to closer access to plumbing. A drain line is also provided from the water cooler into the sewer system.
Water dispensers come in a variety of form factors, ranging from wall-mounted to bottle filler water dispenser combination units, to bi-level units and other formats. They are generally broken up into two categories: point-of-use water dispensers and bottled water dispensers. POU water dispensers are connected to a water supply, while bottled water dispensers require delivery of water in large bottles from vendors. Bottled water dispensers can be top-mounted or bottom-loaded, depending on the design of the model.
Bottled water dispensers typically use 5-gallon bottles commonly located on top of the unit. Pressure coolers are a subcategory of water dispensers encompassing drinking water fountains and direct-piping water dispensers. Water cooler may also refer to a primitive device for keeping water cool.

History

The water dispenser was first invented in 1906 by Luther Haws.

Dispenser types

Wall-mounted / recessed

The wall-mounted type is connected to the building's water supply for a continuous supply of water and electricity to run a refrigeration unit to cool the incoming water, and to the building's waste disposal system to dispose of unused water. Wall-mounted water coolers are frequently used in commercial buildings like hospitals, schools, businesses, and other facilities where a facility manager is present to monitor its installation and maintenance.
In the standard wall-mounted cooler, also commonly referred to as a water fountain or drinking fountain, a small tank in the machine holds chilled water so the user does not have to wait for chilled water. Water is delivered by turning or pressing a button on a spring-loaded valve located on the top of the unit, that turns off the water when released. Some devices also offer a large button on the front or side. Newer machines may not have a button at all; instead, a sensor that detects when someone is near and activates the water. Water is delivered in a stream that arches up, allowing the user to drink directly from the top of the stream of water. These devices usually dispense water directly from the municipal water supply, without treatment or filtering.
Wall mount water coolers come in a wide variety of styles, from recessed models to splash resistant, contoured basins protruding out from the wall, traditional rounded square edge designs, bottle filler and water cooler combination units, bi-level designs, with other features and options. These are sometimes installed to meet local, state or federal codes.

Bottom-load water dispenser

Water dispensers commonly have the water supply vessel mounted at the top of the unit. Bottom-load water dispensers have the vessel mounted at the bottom of the unit to make loading easier.

Tabletop water dispenser

There are also smaller versions of the water dispensers where the dispenser can be placed directly on top of a table. These dispensers are commonly classified as household appliances and can often be found in household kitchens and office pantries.

Direct-piping water dispenser (POU)

Water dispensers can be directly connected to the in-house water source for continuous dispensing of hot and cold drinking water.
It is commonly referred to as POU water dispensers. POU units are generally more hygienic than bottled water coolers, provided the end user has access to clean water sources.

Freestanding

A freestanding design generally involves bottles of water placed spout-down into the dispensing machine.
Tabletop or kitchen worktop versions are available which utilize readily available five-liter water bottles from supermarkets. These coolers use air pumps to push the water into the cooling chamber and Peltier devices to chill the water.
New development within the water cooler market is the advent of countertop appliances which are connected to the mains and provide an instant supply of not only chilled water but also hot and boiling water. This is often visible in the horeca industry.
Water will flow faster when the handle is in the upright position. The water is aerated which allows the water to come through the spout at a faster rate.

Water source

Water dispensed from water coolers may originate from many different sources, but are often classified into two major categories, namely natural mineral and spring water, and purified water.

Natural mineral and spring water

Natural mineral and spring water are waters emanating from underground geological rock formations collected from boreholes or emerging springs. Legislation in each respective country further differentiates between these two types of water and stipulates strict naming and labeling criteria based on natural source protection, total dissolved solids, and the amount of processing the water may undergo prior to bottling.

Purified water

Purified water is water from groundwater or municipal water supply and is produced by any one of several methods of purification including reverse osmosis, distillation, deionization, and filtration. The water is often treated by ultraviolet light or ozone for antimicrobial reasons and re-mineralized by injection of soluble inorganic salts.

Water delivery

The delivery of water in a water cooler comes in two main forms, namely bottled variants, or plumbed directly from the main water supply. The water is normally pumped into a water tank to be heated or chilled, depending on the model of the water cooler. Modern versions include hybrid models that are able to utilize both methods.

Bottled water coolers

To install the bottle, the bottle is tipped upside down and set onto the dispenser; a probe punctures the cap of the bottle
and allows the water to flow into the machine's internal reservoir.
These gravity-powered systems have a device to dispense water in a controlled manner.
These machines come in different sizes and vary from table units, intended for occasional use to floor-mounted units intended for heavier use. Bottled water is normally delivered to households or businesses on a regular basis, where empty returnable polycarbonate bottles are exchanged for full ones. In developing markets, PET is often used for large bottles despite shrinkage and lower washing temperature will lead to making it a more challenging material to use.
The bottle size varies with the size of the unit, with the larger versions in the US using bottles. This is also the most common size elsewhere, labeled as 18.9 liters in countries that use the metric system. Originally, these bottles were manufactured at 3,5 or 6 US gallon capacity and supplied to rented water cooler units. These units usually do not have a place to dump excess water, only offering a small basin to catch minor spills. On the front, a lever or pushbutton dispenses the water into a cup held beneath the spigot. When the water container is empty, it is lifted off the top of the dispenser, and automatically seals to prevent any excess water still in the bottle from leaking.

Material

For many years and throughout the 20th century, glass was the main material used for bottling until the evolution of thermoplastics following World War II. PVC evolved as a multi-purpose plastic material and gained mass adoption as an ideal mass production material. Only dark green glass bottles were retained for packaging carbonated waters. The 1980s saw the re-development of PVC bottles due to cost reduction. Advances in manufacturing and materials technology such as new blow and injection molding techniques have reduced the wall thickness and weight of bottles while improving durability and increasing service life.

Direct plumbed

Directly plumbed water coolers use tap water and therefore do not need bottles due to their use of the main water supply. Usually, some method of purification is used. Log reduction is used as a measure on the effectiveness of sanitization and disinfection.

Purification

Filtration

Filtration methods include reverse osmosis, ion exchange, and activated carbon. Reverse osmosis works differently from chemical or ultraviolet protection, using a membrane that has fine pores, passing H2O while preventing larger molecules such as salts, carbonates, and other micro-organisms from passing through it. If there is insufficient energy to naturally force the water through the membrane, a powerful pump is required, resulting in potential high energy costs. In addition, RO units are capable of softening water. Some living micro-organisms, including viruses, are capable of passing through an RO unit filter.
Deionizers or demineralizers use resins exchange to remove ions from the stream of water and are most commonly twin-bed or mixed-bed deionizers. It is often used in sterile manufacturing environments such as computer chips, where deionized water is a poor conductor of electricity.
In activated carbon, raw materials such as lignite, coal, bone charcoal, coconut shells, and wood charcoal are used, developing pores during activation when partly burning away carbon layers. In most cases, activated carbon is a single-use material as regeneration is often not possible on-site. Granular activated carbon is most commonly used in the filtration of the water cooler. Regular sanitization using hot water and steam is required to limit bacterial growth.

Sanitization & disinfection

The sanitization of water is defined by the reduction of the number of micro-organisms to a safe level. According to the AOAC suspension test method, a sanitizer should be capable of killing 99.999% of a specific bacterial test population within 30 seconds at 25 °C. Sanitizers may or may not necessarily destroy pathogenic or disease-causing bacteria. The sanitizer used must comply with regulations applicable in the geographic location. In the US, sanitizers are regulated by the EPA and FDA, and must pass the AOAC test in the reduction of microbial activity of two standard test organisms from a designated microbial load by a 5-log reduction.
The main difference between a sanitizer and a disinfectant is that at a specific use dilution, the disinfectant must have a higher kill capability for pathogenic bacteria than that of a sanitizer. If these micro-organisms are not destroyed, the bottled water being produced may be contaminated.
UVGI is a commonly used disinfection method to kill or inactivate micro-organisms and leaving them unable to perform vital cellular functions. Drawbacks to UV light water purifiers include turbidity. If the fluid is unclear, the UV light will not pass through completely, leaving the stream partially sterilized.