fig1 and 2 show the exterior configuration of a conventional single handle mixing valve type faucet 10 , the exterior configuration of the single handle mixing valve type faucet 110 of the present invention being substantially the same . the single handle mixing valve type - faucet 10 includes a base 12 , a housing 14 , a valve cartridge 16 located within housing 14 , a valve adjustment stem 18 extending upwardly from valve cartridge 16 , a spout 20 , and a handle assembly 30 . handle assembly 30 includes a grip portion 32 and a socket portion 34 . the upper end of housing 14 is a domed cap 15 having a central circular opening 17 through which stem 18 passes . socket portion 32 of handle assembly 30 fits over and slidingly engages the outer surface of domed cap 15 in a manner well known in the art . valve cartridge 16 can be any conventional valve mechanism used with single handle mixing valve type faucets , and has hot and cold water inlet ports ( not shown ) and a mixed water outlet port ( not shown ) communicating with the water passageway located within spout 20 . the inner end of valve adjustment stem 18 is connected to valve cartridge 16 in the manner used with the particular type of conventional valve mechanism employed . the outer end of valve adjustment stem 18 is connected to handle 30 in any manner used in the art . fig3 shows schematically the various temperatures and flow rates achievable with the conventional single handle mixing valve type faucet 10 during use , with the various zones corresponding to the position of handle 30 . zones a , b , and c represent solely cold water flow , with zone a representing a zero cold water flow rate ( off ), zone c representing a maximum cold water flow rate , and zone b representing solely cold water flow at a rate intermediate zero and maximum cold water flow rates . zones g , h , and i represent solely hot water flow , with zone g representing zero hot water flow rate , zone i representing maximum hot water flow rate , and zone h representing a solely hot water flow rate intermediate zero and maximum hot water flow rates . zones d , e , and f represent water flow having a temperature intermediate that of solely hot or solely cold water , i . e ., warm water . zone d represents zero warm water flow rate , zone f represents maximum warm water flow rate , and zone e represents a warm water flow rate intermediate zero and maximum water flow rates . when a user of conventional faucet 10 is finished with his or her use and desires to turn it off , the typical user will merely bring the handle 30 vertically downward until flow stops . quite often the handle is located in warm water zone e or f or hot water zone h or i during use , and ends up in zone d or g upon shutoff . thus , the next time faucet 10 is turned on , the handle 30 will be moved vertically upward from its shutoff position in zone d or g into either zone e or h , thereby immediately communicating the faucet with the hot water source even though hot water may not be desired . fig5 - 10 illustrate the single handle mixing valve type faucet 110 of the present invention , the reference numbers of parts identical to those of the conventional single handle mixing valve type faucet 10 illustrated in fig1 - 4 being the same but increased by 100 ( fig5 ) or 200 ( fig6 ) or 300 ( fig6 ). the single handle mixing valve type faucet 110 includes a base ( not shown but can be identical to base 12 of the conventional faucet shown in fig1 ), a housing 114 , a valve cartridge 116 located within housing 114 , a valve adjustment stem 118 extending upwardly from valve cartridge 116 , a spout ( not shown but can be identical to spout 20 of the conventional faucet shown in fig1 and 2 ), and a handle assembly 130 : handle assembly 130 includes a grip portion 132 and a socket portion 134 . the upper end of housing 114 is a domed cap 115 having a central circular opening 117 through which passes a valve stem 118 . handle assembly 130 has an outer socket portion 132 which fits over and slidingly engages the outer surface of domed cap 115 . valve cartridge 116 can be any conventional valve mechanism used with single handle mixing valve type faucets , and has hot and cold water inlet ports ( not shown ) and a mixed water outlet port ( not shown ) communicating with the water passageway located within the spout ( not shown ). the inner end of valve adjustment stem 118 is connected to valve cartridge 116 in the manner used with the particular type of conventional valve mechanism employed . the outer end of valve adjustment stem 118 is connected to handle assembly 130 as shown in fig5 and 6 , or in any other manner used in the art . a cylindrical opening 140 is located in that part of socket portion 134 of handle assembly 130 adjacent the inner end of grip portion 132 . a releasable stop member is located within opening 140 . preferably the releasable stop member includes a ball bearing 142 and attached spring 144 . spring 144 is positioned within cylindrical opening 140 , and urges ball bearing 142 outwardly , as shown . a recess 150 extends vertically upward from the base of domed cap 115 to the centrally located opening 117 , and is positioned so that when the grip portion 132 of handle 130 turned to the cold water only position , and regardless of flow rate , ball bearing 142 is urged into contact with the wall of recess 150 by the force of spring 144 . when grip portion 132 of handle assembly 130 is vertically raised to turn on the water , ball bearing 142 , being urged into contact with the wall of recess 150 by spring 144 , resists grip portion 132 from being inadvertently turned horizontally , thereby preventing hot water from being introduced into valve 116 . if warm or hot water is needed , sufficient horizontal force must be applied to grip portion 132 in the direction of the hot water only zone to overcome the compression resistance of spring 144 and thereby cause ball bearing 142 to retract out of contact with the wall of recess 150 . recess 150 can be substantially l - shaped in cross - section , as shown , or any other suitable cross - sectional shape , such as semi - circular . a ramp 160 slopes downwardly around the lower peripheral portion of domed cap 115 from the hot water only zone h ( fig7 ) to the intersection of cold water only zone a ( no flow ) and cold water only zone b ( intermediate flow ). if during use the grip portion 132 of the handle 130 is positioned outside the cold water only zones a , b , or c , any attempt to turn off the faucet by lowering grip portion will fail as ball bearing 142 will come into contact with ramp 160 , thereby preventing further downward movement of the handle . in order to complete turning off the faucet the user must turn the grip portion 132 to one of the cold water only flow zones b or c to cause ball bearing 142 to come into contact with recess 150 and out of contact with ramp 160 , thereby allowing the grip portion 132 to be vertically lowered into the cold water only no flow zone a and the flow stopped . the slope of ramp 160 is adapted to guide movement of grip portion 132 from an on position in zones h or e to the to the off position in zone a . fig7 schematically illustrates the operation of faucet 110 of the present invention . since faucet 110 cannot be shut off in any position except zone a ( cold water only , no flow ), a user desiring to turn the faucet on is forced to raise the grip portion 132 vertically upward into cold water only zones b or c . ball bearing 142 is in contact with the wall of recess 150 which resists inadvertently turning the grip portion horizontally into a warm water zone . when only cold water is desired , the faucet can be turned off by merely moving grip portion 132 vertically downward into zone a ( cold water only , no flow ). if warm or hot water is desired the user must apply enough horizontal force in the direction of the hot water zones to cause spring 144 to compress and remove ball bearing 142 from contact with the wall of recess 150 . when the user is finished and desires to turn off the water , downward movement of the grip portion 132 in any zone but cold water only zones b and c will bring ball bearing 142 into contact with ramp 160 and prevent the water from being shut off . in order to complete shutting off the water the user must move the grip portion 132 rightward into one of cold water only zones b or c , and then continue downward movement of the grip portion into cold water only no flow zone a . fig6 shows two alternative embodiments relating to the placement of the releasable stop member ( i . e ., ball bearing 142 and spring 144 ), recess 150 and ramp 160 . in a first alternative embodiment shown in fig6 , the releasable stop member is moved 180 degrees around socket portion 234 of handle assembly 230 , as shown by ball bearing 242 and spring 244 . an associated recess and ramp ( not shown ) located on domed cap 215 would similarly be moved to function in the same manner as recess 150 and ramp 160 function relative to the releasable stop member ( i . e ., ball bearing 142 and spring 144 ) of fig5 . in a second alternative embodiment ( shown in phantom in fig6 ), the releasable stop member comprised of ball bearing 342 and spring 344 are located in a cylindrical opening 340 in domed cap 215 , and an associated recess and ramp ( not shown ) would be located in the underside of socket portion 234 of handle assembly 230 in that area located below grip portion 232 to function in the same manner as recess 150 and ramp 160 function relative to the releasable stop member ( i . e ., ball bearing 142 and spring 144 ) of fig5 . it will be obvious to those having skill in the art that many changes may be made to the details of the above - described embodiments of this invention without departing from the underlying principles thereof . the scope of the present invention should , therefore , be determined only by the following claims .