This invention relates to a water purification apparatus, and more particularly to water purifiers for household use which are portable, self-contained, and do not require connection to plumbing.
A variety of household devices for obtaining purified water exist in the art. Typically, those devices require connection to a municipal water supply in order to provide pressure to force the water through the filter media. U.S. Pat. Nos. 4,681,677 to Kuh, and 4,502,953 to Marsh are examples of such systems. Systems which must be attached to a tap or plumbing, however, have been found to be expensive to install and maintain, and are obviously unsuitable for use outside the home. Moreover, emergency situations may arise in which the pressure of the municipal water supply may be interrupted, rendering such devices inoperative.
While several domestic water purifiers which require no connection to plumbing have been placed on the market, each of those devices has been found to be deficient in several respects. The BRITA.TM. brand water filter system, for example, is representative of a class of portable devices which utilize gravity to draw water through a filter cartridge containing activated carbon and an ion exchange resin. However, because the water drips through the filter at an extremely slow rate, the available supply of purified water at any given time is limited.
The REGAL PUREWATER.TM. system is representative of another type of a domestic water purifier which includes an electric heating element that heats the water to kill bacteria. In addition to being slow-acting, the water emitted by the device is hot and therefore usually must be cooled prior to use.
U.S. Pat. No. 3,950,253 to Stern discloses a domestic water filtration apparatus which does not require connection to a municipal water supply and which avoids many of the disadvantages of the aforementioned prior art portable devices. The apparatus disclosed in the Stern patent utilizes an electric pump for positively pumping untreated water from a reservoir compartment through a filter medium and into a beaker. Although the purification process is relatively rapid compared with prior art drip-through systems, the heat generated by the electric pump renders the purified water somewhat tepid, thereby requiring removal of the beaker and separate refrigeration of the water prior to consumption as drinking water.
A further disadvantage of the apparatus disclosed in the Stern patent is the fact that the electric pump, once energized, continues to operate until de-energized by the user. Hence, the user must stand by the machine and wait until the purification process is complete to turn off the pump when the reservoir is empty.