Water purification device and method

A vessel is provided with a flexible plastic tube containing an electrical contact switch. Impure water is added to the vessel between the tube and the wall of the vessel. The vessel is then placed in a home freezer. Upon partial freezing of the impure water, the ice expands to flex or compress the tube to close the switch so as to actuate a detector or alarm. The user then removes the unfrozen water, and allows a fraction of the ice to melt. The just formed water is checked for purity by a conductivity measurement. If impure, the water is removed, and the ice is allowed to further melt until the desired purity level is reached at which time the remaining ice is melted to obtain purified water. The device and method are particularly suitable for home use to economically obtain purified water.

FIELD OF THE INVENTION 
This invention relates to the making of fresh or pure water free of 
contaminants. 
BACKGROUND OF THE INVENTION 
The diminishing availability of water that is fit for consumption by humans 
has become a world-wide problem in the last decade. Industrial wastes and 
household chemicals, as well as leachates from cesspools and septic tanks 
are finding their way into the aquifers and surface water supplies. People 
are alarmed by reports of carcinogens and heavy metals, such as lead, 
cadmium, and the like, in their water. 
Many people having lost confidence in the purity of their daily water 
supply, have chosen alternate supplies of drinking water. These water 
supplies are obtained by activated carbon filtering, reverse osmosis 
systems, distillation, and bottled water originating from diverse sources. 
Each of these supplies has some disadvantages which are briefly summarized 
as follows: 
Activated carbon filtering removes only organic contaminants and does not 
remove lead, sodium, nitrates, and the like. Also, the carbon chamber can 
become a breeding ground for bacteria which find their way into the 
so-called purified water, and may be harmful. The activated carbon filters 
must be replaced periodically. 
Reverse osmosis systems are expensive to purchase, are energy intensive to 
operate, and require periodic replacement of expensive components. 
Distillation systems are expensive to purchase, expensive to operate, and 
the heating source must eventually be replaced. 
Bottled water is inconvenient and heavy to carry home from the store, and 
is costly to purchase over a period of time. There is also no guarantee 
that the quality of the water is that which the user desires and is in 
fact an improvement over tap water or other readily available water. 
Various attempts have been made to purify water by freezing or partial 
freezing, such as are disclosed U.S. Pat. No. 2,340,721, granted Feb. 1, 
1944 to Whitney; U.S. Pat. No. 4,448,032, granted May 15, 1984 to Hibino 
et al; and U.S. Pat. No. 4,799,945, granted Jan. 24, 1989 to Chang. These 
systems were complex and costly so as to militate against home use. 
It was also known to measure the purity of water by conductivity 
determinations and other means, such as is disclosed in U.S. Pat. No. 
4,762,611, granted Aug. 9, 1988 to Schipper; U.S. Pat. No. 4,496,906, 
granted Jan. 29, 1985 to Clack; U.S. Pat. No. 3,838,774, granted Oct. 1, 
1974 to Dolan etal; and U.S. Pat. No. 4,752,740, granted June 21, 1988 to 
Steiminger. These systems did not however lend themselves to home use by a 
lay person. 
With the increasing popular demand and need for pure water in the home, it 
was desired to provide a low cost and yet efficient device and method for 
obtaining purified water from impure water. There is now provided by the 
present invention a low cost device which is readily operated by a lay 
person and which provides purified water from tap water by a partial 
freezing method utilizing the home freezer. 
SUMMARY OF THE INVENTION 
The foregoing objectives are achieved by providing a vessel for receiving 
impure water with a member disposed in the vessel, such that upon partial 
freezing of the water in a home freezer or other convenient sub-freezing 
environment, the ice expands to cause the member to compress to close a 
switch to actuate an alarm or indicator so as to alert the user that a 
desired level of partial freezing has occurred. The user then removes the 
unfrozen water from the vessel, and allows ice to melt. The just formed 
water is analyzed by a conductivity meter of specialized design, to 
determine the water purity. Integral to this method is an electronic water 
quality meter which allows the operator to know when to perform a 
significant step in the procedure, namely, whether to discard the melt 
water, and to additionally determine if the method was performed properly 
so that the desired degree of purification of the final product was 
obtained. If the purity level is not that which is desired, the water is 
removed and ice is allowed to melt, and the conductivity measurement 
repeated, until the desired purity is achieved, at which time, all the ice 
is melted to obtain a volume of purified water. 
In another aspect, the present invention is a specialized conductivity 
meter particularly useful in achieving this home use water purification. 
In still another aspect, the present invention is a device as described 
above in which the partial freezing detecting member and water purity 
detection device are operated in a simple efficient manner for ready use 
in the home. 
The partial freezing detecting member is a flexible or compressible plastic 
tube closed at its lower end, and containing an electrical contact switch 
which is normally open. The switch is electrically connected to an 
indicator or alarm. The tube is placed in the vessel, and the vessel 
filled with impure water between the outside of the tube and the inside 
wall of the vessel. Alternatively the impure water may first be added to 
the vessel and the tube then placed in the vessel. The vessel is then 
placed in a home freezer, and upon partial freezing, the ice expands to 
compress the tube to actuate the switch to set off the indicator or alarm. 
The user is alerted to the fact that partial freezing has occured and then 
removes the unfrozen impure water. The user then allows a small portion of 
the ice to melt. This portion of melt water is tested by a conductivity 
meter to determine the purity, and if not sufficiently pure, the water is 
removed, and a portion or fraction of the ice is allowed to melt and then 
retested for purity. This procedure is continued until purified water is 
obtained, and all the residue ice is allowed to melt.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1-3 there is shown one embodiment of the present 
invention 10. Device 10 is, in general terms, composed of vessel 11, cover 
12 having hole 13, plastic tube 14 removably receivable in hole 13, 
freezing determination assembly 15 in operable combination with tube 14, 
and water purity conductivity meter 50 (FIG. 3). Vessel 11 may be of any 
desired configuration and is composed of inert material so as not to 
contaminate the water. Tube 14 is of cylindrical shape having closed end 
18 and open end 19. Tube 14 is preferably formed of food grade plastic. In 
addition, tube 14 is more flexible or compressible than vessel 11, for 
purposes hereinafter appearing. 
Assembly 15 is formed of electrical contact switch 20, which has one 
electrical contact 21 mounted to one inside portion 22 of tube 14, while 
the opposed contact 23 is mounted to opposed inside portion 24. Contacts 
21 and 23 are electrically connected, in series, through wire 25 to 
battery or power source 26, audible alarm 27 and visual indicator 28. When 
wall portions 22 and 24 are compressed, contacts 21 and 23 are contacted 
and the circuit of assembly 15 is closed to actuate alarm 27 and indicator 
28. 
Referring to FIG. 1, the vessel 11 is shown filled with water 30 disposed 
between the outside 31 of tube 14 and the inside 32 of vessel 11. Cover 12 
is designed to hold the water in place so that with freezing the ice 
expand and preferably compresses tube 14 as opposed to raising cover 12 or 
outwardly expanding vessel 11. Vessel 11 and tube 14 may be designed so 
that with a degree of partial freezing, tube 14 compresses and the alarm 
and indicator are actuated to alert the user to the partial freezing. 
The conductivity meter 50 of the present invention responds only to a 
relatively small range in the conductivity spectrum of water. This 
spectrum goes from greater than 45,000 micromhos for sea water to a 
maximum of 700 micromhos for potable water to 300 micromhos for typical 
well water. The conductivity meter of the present invention responds only 
to the range of from about 20 micromhos to 5 micromohs which is the 
conductivity range of the pure water produced by the present invention. 
The meter of the present invention is not of conventional 
electro-mechanical design with a moving needle. This is so because at the 
high sensitivities required by the present invention, these conventional 
devices are very fragile and easily damaged. 
Referring now to FIG. 3, the conductivity meter 50 of the present the 
invention uses several light emitting diodes 51, 52, 53, and 54 to 
indicate the quality of the pure water. When the water is sufficiently 
pure, the first diode 54 glows thus indicating that the water has reached 
the first level of acceptability. As the melting process continues, a 
second light emitting diode 53 will glow (i.e. 2 lights on) indicating 
increased purity. Continuing, a third light 52 comes on (i.e. 3 lights on) 
and finally, if the highest desired level of purity can be reached, a 
fourth light 51 comes on (i.e. 4 lights on). This invention, therefore, 
allows a non-technical operator to readily observe small changes in 
conductivity and to clearly relate those changes to the purity level being 
achieved. 
The meter circuit employs a sample cup 55 which has two cylindrical, 
parallel electrodes 56 and 57 with a space between. The water to be 
examined is poured into or received in the cup. Current now can flow from 
a battery or other power source 60a (V+) to one electrode, into and 
through the water to the other electrode, then through a resistor R6 to 
ground. As the impurity level of the sample decreases, the conductivity of 
the liquid decreases, allowing less current to flow through the circuit, 
causing the voltage at point A to decrease. Conversely, if the impurity 
level of the liquid rises, the conductivity increases allowing more 
current to flow through the circuit, and thereby causing the voltage at 
point A to increase. 
The voltage at point A is conveyed to all of the positive inputs 
(non-inverting) of the comparator C. The negative (inverting) inputs of 
the comparator are connected in a sequential manner to a voltage divider 
consisting of five resistors R1-R5 connected in series between a power 
source 60a and ground. Therefore, the junction between the resistor R1 
that has one of its leads grounded, and the next resistor in series with 
it is connected to the negative input of the first comparator C1. 
Accordingly, the junction between this latter resistor R2 and the next one 
in series with it, namely R3, is connected to the negative input of the 
second comparator C2 and so on. The resistance values of these resistors 
create a constant voltage at each of these four junctions, and measuring 
from ground, each junction will have a higher voltage than the preceding 
one closer to ground. 
With the cup empty no current can flow through the R6 resistor since it is 
an open circuit and therefore the voltage at point A and the positive 
input of the comparators will be zero. The voltage at the negative inputs 
will be positive with respect to ground or point A as a result of the flow 
of current through the 5 resistor voltage divider. These are the reference 
voltages. Under these conditions, the comparator output will assume a 
logic low state approximating ground. The circuit conveys the output of 
the comparator to the cathodes of the LEDs, causing all the LEDs to be 
forward biased and thereby in a conducting state causing the emission of 
visible light from them. If very pure water is placed into or is received 
in the sample cup, the voltage at point A will rise, but not high enough 
to reverse the voltage across the comparators. As the purity of the sample 
decreases, the voltage polarity at point A will eventually rise higher 
than the first reference voltage at the negative input of comparator Cl 
and then the output of comparator Cl will change to a high logic state. 
This will reverse bias the LED wired to Cl causing it to cease to conduct 
current and extinguish the light output. The logic state of C2, C3 and C4 
will not change yet, 3 lights will still be on. 
The resistance valves for R1, R2, R3, R4 and R5 are 5.1K ohms, 3.3K ohms, 
3.3K ohms, 3.3K ohms and 62K ohms, respectively. Comparator C may be a 
LM339 quad comparator. 
As the impurity level of a new sample increases, the voltage at A will 
continue to increase eventually rising higher than the reference voltage 
at C2 causing that output to change state and extinguish its associated 
LED. It can be seen that following this pattern, eventually all of the 
LEDs will turn off, indicating that the water is no longer in the 
acceptable pure range. Zener diode D, or alternatively a limiting resistor 
R7 (1K ohm), limits the current through the LEDs to a safe level and 
completes the circuit. R7 is shown as an alternative element in broken 
line in FlG. 3. 
Referring to FIGS. 4-6, There is shown an embodiment of the invention 60. 
Device 60 is formed of vessel 61 having rigid walls 60 with tapered bottom 
portion 68, discharge valve 62 and support base 63. Cover 64 is provided 
to tightly enclose water sample 65 in vessel 61, and cover 64 is provided 
with hole 66 to receive tube 67. 
A partial freezing determination device 70 is shown disposed in flexible 
plastic tube 67. Device 70 is similar to device 15 as hereinbefore 
described having audio alarm 128 and visual indicator 127. Tube 67 is 
similar in design and construction to tube 14 hereinbefore described. A 
conductivity meter 75 is of similar design to that of meter 50, except 
that it is operably combined with tube 67 and vessel 61. Specifically, 
sample cup 76 is disposed at the end of tube 67, and is disposed adjacent 
the bottom 78 of vessel 61. The wires 79 connect the electrodes of sample 
cup 76 with the operative electronic components in housing 80. The four 
LED's 81-84 indicate the different purity levels in a manner as previously 
described in connection with the embodiment of FIGS. 1-3. 
In this manner of construction, device 60 is operated by the user filling 
vessel 61 with water 65, with valve 62 closed. The cover 64 then tightly 
encloses vessel 61. The user then inserts tube 67 with freezing 
determination device 70 and conductivity meter 75 (FIG. 4). The user then 
places the device 60 in a home freezer. Upon partial freezing, ice 81 
expands to compress tube 67 and actuate the freezing determination device 
as aforediscussed. Alarm 128 signals the user (FIG. 5). The user removes 
the device from the freezer. The user then opens valve 62 and allows the 
unfrozen impure water to flow out of the vessel. Valve 62 is then closed. 
The user then allows ice to melt until the melt water causes one or more 
of the LED's 81-84 to light, indicating the desired level of purity. The 
user has the option of discarding the melt water if not at the desired 
purity level. When the desired purity is reached, the user allows the 
remaining ice to melt, and places a clean collection vessel or plastic 
container 85 under valve 62, opens valve 62 and allows the pure water to 
be collected in container 85. The user can also readily monitor the water 
purity as it is being collected to assure the desired purity level of the 
collected water. 
The following example illustrates the method of the invention in 
conjunction with the embodiment of FIGS. 1-3. 
EXAMPLE 
1. The container or vessel is filled with the sample of water to be 
purified. 
2. The insert tube or member is positioned in the vessel, with the cover 
holding the tube in the vessel thereby enclosing the sample. 
3. The container is placed in a freezer compartment of a home freezer. 
4. When the tube member indicator is activated, the container is removed 
from the freezer environment. The insert tube is removed and the liquid 
(unfrozen) portion is poured off. 
5. Some melting of the ice is allowed to occur and the melt water is tested 
with the electronic water quality tester or conductivity meter. 
6. If the first (lowest purity) indicator lights, the rest of the ice is 
allowed to melt. Step No. 8 is then followed. 
7. If no indicator lights, the accumulated melt water is poured off and 
another small quantity of melt water is allowed to accumulate. The new 
melt water is tested, and this step is repeated until the first indicator 
lights. When the first indicator lights, the remaining ice is allowed to 
melt. 
8. When only a small amount of ice remains, the melt water is again tested 
to re-determine the quality of purified water produced. 
It is important to note that with 1 or 2 indicator lights on, the water has 
less impurities than any tap water or bottled water. A level of 3 
indicator lights on is readily achieved by the present invention and 
indicates very pure water. A level of 4 indicator lights denotes water 
with 95% to 99% or more of the impurities removed. 
The tube of the present mention, in addition to the aforesaid functions, 
aids in the partial freezing by providing additional surface for freezing; 
allows the cold air to flow on the inside of the tube; prevents the vessel 
from rupturing; is removable to allow ice to melt and keeps contaminents 
out of the vessel. It is also to be noted that in allowing the ice to 
partially melt, the water impurities concentrate at the ice surface and 
thus on melting the impurities are in the melt water to be discarded. 
While a particular embodiment of the invention has been shown and 
described, it will be obvious to those skilled in the art that changes and 
modifications may be made without departing from the invention in its 
broader aspects, and, therefore, the aim in the appended claims is to 
cover all such changes and modifications as fall within the true spirit 
and scope of the invention.