OSA WATER WORKS

Potable Water Supply

Dependable, potable water as a renewable resource is one of the global environmental obstacles that has grown more acute as a result of population increase and changes in global climate patterns.  While water treatment technologies are employed throughout the world to ensure that municipal water delivery is free of pathogens that cause diseases, the majority of the world still does not enjoy the high standards of municipal water quantity and quality enjoyed by industrialized societies and some developing nations, including Costa Rica.  

Design drawings for installation of drainage, water supply, pollution control, and power distribution for a five cabina and restaurant complex near Uvita, Costa Rica.

Even where water quality is ensured by chlorination or other forms of bacterial and viral disinfection, the sheer demand in many parts of the world that do not have abundant water resources, including many parts of California, for example, frequently outstrips supply, and crisis management contributes to the unsustainable development of vulnerable sources and to enforce water-rationing measures as needed.

Installation of a four-chamber Infiltration Gallery

Even in tropical rain forests, the development of an environmentally responsible domestic water supply is not as simple as it would appear.  This is particularly true if additional water use possibilities include hydroelectric power generation, irrigation, and pool water supply.  Alternatives typically available to landowners for water supply include the following.

Springs.  While springs typically represent a source of high water quality and often sufficient supply for a residence or a remote commercial lodge, removal of this water deprives the environment of stream flow during the summer months, when there are no rains to engender run off and corresponding stream flow.  Springs derive their water from ground water, which commonly contains a relatively high dissolved mineral content.  Correspondingly, water softening treatment of spring water is sometimes necessary for optimal domestic consumption; however, spring water rarely requires either disinfection or particulate filtration.

Small spring with a discharge of 3 gpm, capable of satisfying the domestic water demand of up to 43 full-time users (Río Oro, Costa Rica).

Surface Water.  Perennial streams (ones that carry water year round) represent sources of often abundant water but that require water treatment for removal of sediment as well as disinfection to neutralize pathogens almost universally present in stream water.  Osa Water Works has developed a proprietary intake filtration design for surface water systems that is completely maintenance free, which excludes over 99% of suspended sediment even during storm runoff when surface water runs turbid, and has a lifetime guarantee.  Our infiltration galleries come in sizes capable of delivering as little as 5 gallons per minute for very small streams to upwards of 5,000 gpm for modestly sized streams for hydroelectric power purposes. 

Jungle stream with a flow rate capable of sustaining a small community with potable water (Costa Rica).

Ground Water.  Wells represent an often ideal source of domestic water supply that can provide the yields necessary for potable water demand and which are commonly free of contaminants and don't require water treatment.  Well development is often complicated in remote building sites, however, by difficulties in access for well-drilling equipment and by often high associated costs.  Subterranean water flow and water quality are strongly dependent upon geology, and well water is not a universal solution to water supply.  Any decision to sink a well should be preceded by a detailed hydrogeological assessment of the area.  While wells often produce water that requires no treatment for bacteria, mineral content is commonly high, and water softening treatment may be required to remove calcium and magnesium hardness.  Iron and manganese are nuisance contaminants common to well water systems that may also need to be removed through water treatment.  Whereas spring and surface water intakes may be able to provide gravity pressure for end use, wells always require system pressurization, either through water towers, or using a pressure tank.

Pump test on a hand-dug well (Matapalo, Costa Rica)

Municipal Water Supply.  Pre-existing municipal water supply is often the easiest alternative for building sites where this is available.  Often this involves capitalizing the pipeline necessary to connect to a trunk line.  Activated carbon filtration may be desirable to remove residual chlorine used to disinfect municipal water supply.  Often, especially in underdeveloped region, excess chlorine is employed to ensure disinfection, and chlorine and a series of chlorine metabolites are known carcinogens.

Rainfall Capture.  For areas that experience significant annual rain, rainfall capture systems are often the most environmentally friendly solutions to remote water supply.  These systems include a roof that channels rainfall runoff and a storage tank with sufficient capacity to sustain adequate water supply during the driest period of the year.  The adequate design of such a system requires detailed information about annual precipitation patterns and the demand expected from the structure.  A filtration and disinfection system is always needed for rainfall capture systems to ensure that water remains contaminant free, and pressurization is required through either a water tower or pressure tank.

Rainfall capture for household potable consumption

Water Distribution and Storage.

The design of water distribution systems is predicated upon the proper balance between yield and cost.  In practice, the design criteria revolves around the potential and kinetic energy of water.  Pipeline and storage tank sizing are vital for optimizing system performance and reducing pumping costs.  In strictly gravity systems, pipeline sizing directly governs delivery pressure.  Tank sizing is vital in order to provide adequate water supply from a very small source.  The same principles in distribution system design apply whether the intended use is domestic potable, hydroelectric, or irrigation.  Our system designs present project managers with the information necessary to balance capital and operating costs in order to select the most appropriate design for delivery of the needed flow and pressure.

Water Purification.

Chemical analysis of water sample for design of most appropriate modular home purification system.

Most domestic water supplies require some form of water treatment, commonly limited to filtration and disinfection.  For well and spring water sources, advance water quality tests will determine if treatment for bacteria or for nuisance mineral contaminants are necessary.  For surface-water and rainfall capture domestic water supplies, water treatment is universally necessary for the removal of suspended sediments and bacteria.  Water quality tests should always be conducted in advance of the final potable water system design to ensure that needed contaminant mitigation systems are in place.  These are necessary not only for the exclusion of microbiologic pathogens for the protection of human health but also to ensure that mineral water quality is adequate so that scale does not build up in pipe walls to reduce the lifetime of the distribution system and that iron and manganese do not contribute to undesirable taste in water or to the staining of ceramic fixtures.

1.  Gradient Prefilter (75-25 micron) for large sediment
2.  Polishing particulate filter (5 micron)
3.  Granular Activated Carbon
4.  Ultra-violet disinfection
5.  Water softener

OWW's proprietary modular home purification system is predicated on the treatment needs of the water in question.  A laboratory analysis is used to determine the concentration of sediments, fecal and total coliform bacteria, major ions, iron and manganese, and nutrients.  There are four modules that are commonly used:  filtration, granular activated carbon adsorption, ultraviolet disinfection, and water softening.  Almost never are all four modules required for a particular water.  A description of each module is provided below:

Particulate Filtration.  Our particulate filter housing is of a standard size that will allow for a variety of filter types to be used.  Because of the efficiency of the filtration in the water intake, gradient filters often are the best alternative as they are easily washed for reuse and are normally sufficient for particulate removal.

Granular Activated Carbon Adsorption.  For waters that have organic odor or taste, granular activated carbon filters are recommended.  GAC filtration is also the standard technology for removal of chlorine from municipal water systems.

Ultraviolet Disinfection.  Pathogenic micro-organisms and viruses are deactivated through contact with ultraviolet light.

Water Softening.  Removal of multivalent cations is achieved by ion-exchange.  Calcium and Magnesium concentrations are removed to lower carbonate hardness which causes scaling.  Iron and manganese, which cause taste and stain fixtures, are also removed by this process.

Supplemental.  Rarely a supplemental module is incorporated for the removal of a particular nuisance contaminant, like nitrate, hydrogen sulfide, trace metals, excess iron, excess fine sediment, and very rarely synthetic organic contaminants.  Technologies of supplemental purification modules that address these needs include:  pre-filtration, ion exchange, oxidation, and advanced oxidation.

If you would like to ask OWW about your property and possibilities for water supply and distribution for potable, hydroelectric, agricultural, or other uses, fill out our inquiry form here or simply write me an email.

Home    Mission   Hydroelectric Power   Potable Water   Sanitation    Contact Us    Ask OWW