as shown in the accompanying drawings , the present invention is embodied in a spa , indicated generally by the reference numeral 10 , for use in heating and circulating water 12 in the traditional manner . the spa 10 is capable of either above - ground installation , in which a raised deck 14 may be constructed around the spa , or direct in - ground installation , in which the spa is installed in the ground 16 with the earth directly in contact with the side of the spa . in either case , access to the equipment required for service of the spa 10 is convenient and not hindered in any way by the manner of installation . [ 0028 ] fig1 shows the spa 10 installed directly in the ground 16 . however , whether the spa 10 is installed in the ground 16 , as in fig1 or above the ground , as in fig4 the basic structure of the spa is still the same . it is defined by a shell 18 , which may be constructed of fiberglass , acrylic , high - impact thermoplastic materials , or any other suitable lightweight , high - strength material not easily susceptible to damage from water or sunlight . the shell 18 may be molded in a single unit , but more commonly it is a combination of several pieces joined together by adhesives or fasteners or by similar methods known in the art . in one embodiment , the shell 18 comprises an outer wall 20 that defines the outer shape of the spa 10 and functions as a housing to enclose all of the remaining elements of the spa . in particular , the outer wall 20 comprises a vertical side wall 22 and a horizontal bottom wall 24 . a horizontal coping 26 along the upper surface of the spa 10 provides a smooth transition from the vertical side wall 22 to an internal water reservoir 28 designed to hold a quantity of water 12 and at least one person 30 . as shown in fig2 a space 32 is provided between the outer wall 20 and the reservoir 28 . this space 32 is preferably filled with a stiff insulating material 34 , such as a dense styrofoam or the like . the insulating material 34 increases the structural integrity of the spa 10 , as well as its insulating qualities . with reference to fig2 - 3 , a step 36 is included in the reservoir 28 for the user &# 39 ; s ease and safety while entering the spa 10 , and bench seats 38 are included for the user to sit or lounge in the water 12 . a foot well 40 is also typically included in the center of the spa 10 . multiple hydro - jets ( not shown ) located around the perimeter of the reservoir 28 provide powerful streams of heated water that vigorously circulate the water 12 in the reservoir . it will be understood that the arrangement of the step 36 , seats 38 , foot well 40 ( and hydro - jets ) illustrated in the drawings is but one possible configuration , and many other arrangements could be used . in addition , in cases where the spa 10 is installed above the ground 16 , an optional drainage line ( not shown ) originating at the lowest point of the reservoir 28 and terminating outside of the shell 18 may be included to assist in draining of the reservoir . it will be noted that the coping 26 is considerably wider at one side of the spa 10 than any other . the coping 26 is enlarged in this area to provide an opening 42 leading to an equipment bay 44 . the equipment bay 44 has two sections comprising an equipment compartment 46 and filtration compartment 48 , both of which are located between the outer wall 20 and the internal reservoir 28 . preferably , the equipment compartment 46 and the filtration compartment 48 are in close proximity such that a single cover may be used to cover both . however , it is not a necessary requirement of this invention that the filtration compartment 48 and the equipment compartment 46 be located next to each other or that they share a common cover . thus , a cover 50 for the equipment compartment 46 and a cover 51 for the filtration compartment 48 are shown . for convenience , both of these covers will be referred to as the cover 50 . with particular reference to fig2 the filtration compartment 48 includes a skimmer 52 that provides a water flow path from the reservoir 28 to the filtration compartment 48 . thus , the water level in the filtration compartment 48 is maintained essentially at the same level as that in the reservoir 28 . preferably , the lower edge of the skimmer 52 is just below the water level so that only water from the uppermost surface of the reservoir 28 can enter the filtration compartment 48 . the skimmer 52 also preferably includes an inwardly hinged skimmer door 54 or the like that allows water and floating debris from the upper surface of the reservoir 28 to enter filtration compartment 48 . in the event that a wave or backflow causes water from the filtration compartment 48 to flow back into the reservoir 28 , the skimmer door 54 will be forced to close . thus , floating debris that enters the filtration compartment 48 will remain trapped therein until the user removes it during a periodic cleaning . a filter cartridge 56 located near the bottom of the filtration compartment 48 serves to filter impurities in the water before it travels from the filtration compartment 48 through a pipe 58 and on to the equipment compartment 46 . the filter cartridges 56 are removable so that they can be periodically cleaned or replaced . unlike the filtration compartment 48 , the equipment compartment 46 is not flooded with water 12 . it is isolated from the filtration compartment 48 and the reservoir 28 by a vertical wall 60 . the equipment compartment 46 houses a conventional water pump 62 ( or pumps as shown in fig3 ), such as a motor - driven impeller - type water pump . it also houses a conventional water heater 66 for heating the water 12 and maintaining a desired water temperature within the reservoir 28 . a control box 64 houses the necessary controls for controlling operation of the water pumps 62 , the water heater 66 and any other necessary equipment . a sump pump 68 is located in the lower - most portion of the equipment compartment 46 and serves to remove any excess water that might leak or be splashed into the compartment 46 or , when installed in - ground , any water resulting from fluctuation in water table levels . power to operate the water pump 62 and the water heater 66 is supplied from an external electrical source ( not shown ) through a conventional hookup that may be located just below the edge of the coping 26 . the water pump 62 draws water from the reservoir 28 into the filtration compartment 48 and into the water heater 66 through an intake pipe 70 . after passing through the heater 66 , the water 12 is returned to the reservoir 28 by an output pipe 72 that distributes the heated water to the one or more hydro - jets located in various positions around the sides of the reservoir 28 . the intake and output pipes 70 and 72 are preferably constructed of polyvinylchloride , but could also be made of other lightweight , noncorrosive materials . if it is desired to create a low - maintenance water treatment in the reservoir 28 , a feature traditionally associated with spas of this type , the output pipe 72 may also include an ozone generator ( not shown ) that mixes ozone gas with the water flow before it enters the spa 10 . in accordance with the invention , the spa 10 may be installed above ground level , in the manner of a portable spa or , alternatively , it may be installed below ground level , in the manner of a permanently installed in - ground spa . if above - ground installation is desired , as shown in fig4 one simply needs to place the spa 10 on a firm and level area ( such as on a concrete pad or hard - packed earth ), fill the reservoir 28 with water 12 , and connect the power source . since the side walls 22 of the spa are typically several feet high , an elevated deck 14 may also be built around the spa 10 to improve accessibility and appearance . many variations of decks will serve this purpose . importantly , the elevated deck 14 does not require an equipment access door , either in the side or on the top of the deck , in order to gain access to the equipment bay 44 . this is because all of the equipment in the equipment compartment 46 and the filtration compartment 48 can be conveniently reached by removing the cover 50 at the top of the spa 10 . hence , unsightly and potentially unsafe access doors in the deck 14 are avoided , as is the extra expense to make them . moreover , the ease with which the equipment bay 44 can be reached is substantially enhanced . this is no need to crawl under the deck 14 through a side access door , or down through an access door in the top of the deck . when the spa 10 is to be installed below ground level , as shown in fig1 - 2 , a hole just slightly larger than the spa must be excavated . once the spa 10 is placed in the hole , which may be as deep as the edge of the coping 26 , some of the earth 16 that was excavated may be replaced directly around the walls of the spa , thus locking the spa into place . the reservoir 28 can then be filled with water 12 and the power source can be connected . importantly , no retaining wall or other type of barrier needs to be installed to keep the earth 16 away from the side walls 22 of the spa 10 . further , since the spa 10 is a self - contained unit having all of the necessary equipment to operate the spa , there is no need for additional excavation for plumbing , such as output pipes or hydro - jets . again , only the power source needs to be connected , and since it is located just below the edge of the coping 26 , it also does not require additional excavation . thus , the spa 10 may be easily installed in areas where space is limited , and it may be installed in virtually any orientation desired by the user . furthermore , even though the entire side wall 22 of the spa 10 is buried underground , access to the equipment bay 44 is easily and conveniently accomplished through the top access cover 50 in the coping 26 . consequently , there is no need to build a retaining wall or the like around the spa 10 before it is placed in the hole . however , if the appearance of an in - ground spa is desired , and the user wishes to keep the option to move the spa 10 in the future , such a conventional retaining wall could be built . advantageously , since the equipment bay 44 is accessible at the tope of the spa 10 , only a small clearance is necessary between the spa side wall 22 and the retaining wall . when the spa 10 is installed above - ground level , there will be some lateral forces against the walls comprising the reservoir 28 and the outer wall 20 of the shell 18 . for example , the weight of the water 12 in the reservoir 28 creates an outward lateral pressure against the reservoir walls and contributes to the overall weight of the spa 10 and thus the forces exerted on the side wall 22 supporting the spa . even more significant , however , is the lateral pressure against the outer wall 20 caused by the earth 16 when the spa 10 is installed directly in the ground . if the reservoir 28 is empty for a significant time , this lateral inward pressure could cause substantial damage or buckling of the walls without a counteracting support system . accordingly , the present invention provides a reinforcing means to prevent this damage . [ 0043 ] fig5 illustrates one embodiment of a reinforcing means comprising an internal support framework 74 which provides the necessary structural support to enable the side wall 22 of the spa 10 to resist the subjacent lateral forces of the earth 16 resulting from in - ground installation . the support framework 74 comprises a plurality of supports such as pressure treated wood . other suitable supports , such as supports made from rigid plastic material , also can be used . the support framework 74 is located in the space 32 between the reservoir 28 and the outer wall 20 and comprises bottom horizontal supports 76 , top horizontal supports 78 and vertical supports 80 extending between and connecting the top supports 78 to the bottom supports 78 . triangulation of the vertical supports 80 is accomplished by braces 82 having one end connected either to a vertical support 80 or a top horizontal support 78 and having another end connected to a corresponding horizontal bottom support 76 . a dense foam or similar lightweight , high - strength material 34 , discussed above , may also be used as a filler between the outer wall 20 and the reservoir 28 to increase the structural integrity as well as the insulation capacity of the spa 10 . in this regard , it is contemplated that an appropriate filler 34 with the requisite structural strength and other characteristics could be used alone to support the spa 10 , without requiring the support framework 74 discussed above . an alternative embodiment of the invention is illustrated in fig6 . in this embodiment , the equipment compartment 46 and the filtration compartment 48 are accessible from the side of the shell 18 through a side access door 84 . a side shield 86 isolates and protects the side access door 84 from the surrounding earth 16 for an in - ground installation . however , the excavated ground otherwise completely surrounds and abuts against the side wall 22 of the spa 10 , as in the in - ground installation discussed above . from the foregoing , it will be appreciated that the present invention provides a universal self - contained spa 10 that can be installed either above ground or below ground level , while still providing a means to access the equipment necessary to service the spa . access to the equipment is both convenient and safe , and the overall appearance of the spa 10 and its surrounding environment is as aesthetically pleasing as possible . the resulting spa is extremely versatile , as it may be portable or permanently installed at the option of the owner . while a particular form of the invention has been illustrated and described , it will be apparent that various modifications can be made without departing from the spirit and scope of the invention . accordingly , it is not intended that the invention be limited , except as by the appended claims .
a portable spa comprises a reservoir for holding water and an outer wall spaced outwardly from the reservoir . the spa includes an equipment bay located between the reservoir and the outer wall that is accessible from an opening at a top portion of the spa . a cover over the opening to the equipment bay is removable from the top portion of the spa to permit access to the equipment bay . the equipment bay contains substantially all of the equipment necessary for operation of the spa and can be conveniently accessed free of any obstructions around the side of the spa . the spa can be installed either above ground in the manner of a portable spa , or it can be installed directly in the ground in the manner of a permanent in - ground spa . reinforcing means comprising an internal support framework supports the spa against the lateral external forces generated as a result of in - ground installation .