Hotel Engineering Notes-Water

WATER

Water (H₂O) is the most abundant compound on Earth's surface, covering about 70%. In nature, it exists in liquid, solid, and gaseous states. It is in dynamic equilibrium between the liquid and gas states at standard temperature and pressure. At room temperature, it is a tasteless and odorless liquid, nearly colorless with a hint of blue. Many substances dissolve in water and it is commonly referred to as the universal solvent. Because of this, water in nature and in use is rarely pure and some of its properties may vary slightly from those of the pure substance. However, there are also many compounds that are essentially, if not completely, insoluble in water. Water is the only common substance found naturally in all three common states of matter and it is essential for all life on Earth. Water usually makes up 55% to 78% of the human body.

Requirement of water in hotels:

A typical hotel water audit consumption:

Kitchen	Cold Room	Laundry	Steam Gen.	Public Toilet	Pool	Guest Room	HVAC
21%	6%	12%	4%	17%	2%	37%	1%

Importance of water in hotel industry:

For the existence and survival of human life, water is an essential commodity, next only to air. It is essential for life, health and sanitation. It is the principal raw material for food production. It is needed for drinking, bathing, washing body and clothes, washing floors, flushing of WC, gardening, vehicles and road washing,

fountains, air-conditioning, swimming pools, air coolers, brewing, cleaning, fire fighting etc.

	Water requirement in hotels is 180ltrs/bed/day approx. Water for restaurants is 70 ltrs/seat/day approx. Water for gardening is 17000-35000 ltrs/day/hectare.

 

Sources of water supply:

The main source of water supply is rainfall. Rain, snow, hail and sleet are precipitated upon the surface of the earth as meteorological water and may be considered as the original source of all the water supplied. This water gets collected in catchment areas like rivers, lakes etc. from where this water after getting proper filtration treatment by municipal corporation / water supply department / public health engg. department, is distributed for human consumption. The other source of water is underground water. Water, as source of drinking water, occurs as surface water and

ground water. Three aspects should be considered in appraising water resources e.g., the quantity, the quality, and the

reliability of available water. Surface water accumulates mainly as a result of direct runoff from precipitation (rain or snow). Precipitation that does not enter the ground through infiltration or is not returned to the atmosphere by evaporation, flows over the ground surface as direct runoff. Direct runoff is water that drains from saturated or impermeable surfaces, into stream. The rainwater that has percolated into the ground is brought to the surface for our needs. This water replenishes the soil moisture, or is used by growing plants and returned to the atmosphere by transpiration. Water that drains downward (percolates) below the root zone finally reaches a level at which all the openings or voids in the earth's materials are filled with water. This zone is called the zone of saturation. The water in the zone of saturation is called the ground water. The upper level of water in the ground is called ground water level /table. For bringing underground water to the surface, wells are to be dug. A ground well is defined as an artificial hole / pit in the ground for the purpose of tapping ground water. The various types of wells are: a) Shallow wells, b) Deep wells, c) Tube wells, d) Artesian wells. A well that penetrates the water table can be used to extract water from the ground basin.

The extraction of ground water is mainly by:

1. Dug well with or without retaining walls

2. Dug cum bore wells

3. Cavity Bore

4. Radial collector wells

5. Infiltration galleries

6. Tube-wells & bore wells.

Ground water that flows naturally from the ground is called a Spring.

	A tube well is a type of water well in which a long 100–200 mm (5 to 8 inch) wide stainless steel tube or pipe is bored into the underground aquifer. The lower end is fitted with a strainer, and a pump at the top lifts water for irrigation. The required depth of the well depends on the depth of the water table. An artesian well allows water that has travelled through porous rock from a higher elevation to rise to the surface. This pumpless well seems to defy gravity because the pressure that builds up between layers of rock gets relieved when the water finds a path to the open air. For nearly a thousand years, people have drilled wells to drink this cold, filtered water that doesn't need to be hauled up from the depths.
		Rain Water Harvesting: The areas which have a fair amount of natural rainfall, but do not have geographical conditions to absorb and impound the rain water, should have rain water harvesting system. Here the natural rain water is channelised into the sub-soil near the bore-wells / tube-wells, so that the ground water level rises and these wells do not dry up in summer season.

 

Water Quality:

When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.

Raw water obtained from lakes etc.  is not potable and has many defects. These can be:

>>           Volatile and oxidizable impurities

>>           High salt content

>>           Corrosivity and scale formation

>>           Acidic content

>>           Hardness

>>           Bacterial contamination

>>           Odour and foul taste

>>           Suspended impurities

>>           Dissolved impurities

Soft:	0–60 mg/L
Moderately hard:	61–120 mg/L
Hard:	121–180 mg/L
Very hard:	≥181 mg/L

Hard water is water that has high mineral content (in contrast with soft water). Hard water has high concentrations of Ca²⁺ and Mg²⁺ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water. In domestic settings, the hardness of water is often indicated by the non-formation of suds when soap is agitated in the water sample.Hard water interferes with almost every cleaning task from laundering and dishwashing to bathing and personal grooming. Clothes laundered in hard water may look dingy and feel harsh and scratchy. Dishes and glasses may be spotted when dry. Hard water may cause a film on glass shower doors, shower walls, bathtubs, sinks, faucets, etc. Hair washed in hard water may feel sticky and look dull. Water flow in pipes may be reduced by deposits due to hardness. Hardness can be quantified by instrumental analysis. The total water hardness, including both Ca²⁺ and Mg²⁺ ions, is reported in parts per million (ppm) or mass/volume (mg/L) of calcium carbonate (CaCO₃) in the water. Although water hardness usually measures only the total concentrations of calcium and magnesium (the two most prevalent divalent metal ions), iron, aluminium, and manganese can also be present at elevated levels in some locations. The presence of iron characteristically confers a brownish (rust-like) colour to the calcification, instead of white (the color of most of the other compounds).

For the reasons discussed above, it is often desirable to soften hard water. Most detergents contain ingredients that counteract the effects of hard water on the surfactants. For this reason, water softening is often unnecessary. Where softening is practiced, it is often recommended to soften only the water sent to domestic hot water systems so as to prevent or delay inefficiencies and damage due to scale formation in water heaters. A common method for water softening involves the use of ion exchange resins, which replace ions like Ca²⁺ by twice the number of monocations such as sodium or potassium ions. There are two ways to help control water hardness: use a packaged water softener or use a mechanical water softening unit. Packaged water softeners are chemicals that help control water hardness. They fall into two categories: precipitating and non-precipitating.

Precipitating water softeners include washing soda and borax. These products form an insoluble precipitate with calcium and magnesium ions. The mineral ions then cannot interfere with cleaning efficiency, but the precipitate makes water cloudy and can build up on surfaces. Precipitating water softeners increase alkalinity of the cleaning solution and this may damage skin and other materials being cleaned.

Non-precipitating water softeners use complex phosphates to sequester calcium and magnesium ions.  There is no precipitate to form deposits and alkalinity is not increased. If used in enough quantity, non-precipitating water softeners will help dissolve soap curd for a period of time.

Mechanical water softening units can be permanently installed into the plumbing system to continuously remove calcium and magnesium.  Water softeners operate on the ion exchange process. In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium. The ion exchange process takes place as hard water passes through the softening material. The hardness minerals attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a salt (brine) solution through the resin. The sodium replaces the calcium and magnesium which are discharged in the waste water.

Water conservation in hotels:

Hotel Areas for Water Conservation

Cooling Towers, Laundry facilities, Guest Rooms, Toilets/urinals, Showers, Sinks, Laundry needs, Swimming Pools & Spas, Restaurants, Landscaping.

Guest Rooms

Low-volume toilets use 6 ltr per flush (lpf) or less; Dual flush toilets 3.6 lpf or less; Toilet leak repair schedule (deterioration of rubber and thermoplastics from chloramines); Low-volume showerheads use a maximum of 10 lpm (@80 psi); Low-volume bath faucet use a maximum of 10 pm (@80 psi).

Laundry:  wastewater recovery and recycling system options.

Water cooled Icemakers are inefficient unless the refrigeration system recirculates the cooling water.

Swimming Pool: An average uncovered outdoor pool loses about an inch of water a week during the summer because of evaporation! Other losses are: Splashing; Filter Backwashing; and Leaks.

Restaurant Areas for Water Conservation:  Faucet maintenance; Hands-free controls; Presoak instead of running water;

Automatic shut-off for bar sinks; Reduce flows to minimum in wells and troughs; Turn off continuous flows (drain trays); On-demand, point-of-use hot water dispensers; Promptly repair leaks and malfunctioning equipment; Eliminate thawing frozen food with water unless required by law; Avoid running water to melt ice in sink strainers; Wash-down hoses can be

retrofitted with a throttling valve; Use full loads in sanitizers, sterilizers, dishwashers, and washing machines; Replace worn-out fixtures and appliances with water-saving models; Use minimum wares to reduce dishwashing loads; Provide water conservation signs for staff and customers! Water used in hot food buffet tables can be reused for floor cleaning!

Linens: Even if you have linens washed by a commercial laundry – water is being used somewhere! Only wash what you need to wash. Disposables may be an option during the drought!

Point-of-Use Hot Water Demand Units: Hot water supplied to certain faucets, showerheads, and tubs is sometimes used

inefficiently because of heat losses that occur when hot water pipes are poorly insulated or water must travel through long lateral lines to the user. Instantaneous hot water demand unit may prevent this loss!

Landscaping:  Native and Low-Water-Use Turf and Plants; Re-direct condensate to landscape; Electronic Irrigation System Controllers; Rainfall Shutoff Devices; Soil Moisture Sensors; Drip Irrigation; High Level of Maintenance!

Rain Barrels – Cisterns:  A 1000-square-foot roof can collect 150 gallons of water during a quarter-inch rain. Landscapes can be graded to create depressions to catch runoff for redirection to lawn. Cistern water can be used in cooling towers; plant watering; fountains, etc.

Bureau of Indian Standards  IS 10500 : 1991

Some Characteristics For Drinking Water

Parameters	Desirable limits	Permissible limit
Colour Hazen Unit	5	25
Odour	Unobjectionable
Turbidity NTU	5	10
pH	6.5 – 8.5	6.5 –8.5
Hardness (as CaCO3) mg / ltr	300	600
Chloride (as CaCO3) mg / ltr	250	1000
Total Dissolved Solid TDS mg/ltr	500	2000
Calcium (as Ca) mg/l,	75	200
Fluoride (as F) mg/l,	1.0	1.5
Magnesium (as Mg), mg/l,	30	100

Water Distribution Systems in hotels: These are

I) Gravity Systems: It is useful when the source of water supply is situated at a higher level than the distribution area. The water is conveyed through pipes by gravity. Distribution reservoirs / tanks are provided in the distribution system to store clean treated water before it is taken for use by consumers. These reservoirs may be constructed by brick masonary, cement concrete or RCC. Reservoirs may be Surface reservoirs or Elevated reservoirs.

II) Pumping Systems: Water is directly pumped into the mains leading to the consumers. The disadvantage here is that in case of power failure, the total water distribution system collapses.

III) Gravity & Pumping combined: The treated water is pumped and stored in elevated reservoirs and distributed through pipes by gravity. Here the advantage is that even if power fails, water supply is maintained by gravity.

Waste water drainage systems:

Sludge and Rain / Storm water drains: i) Street drains placed alongside the road kerbs, discharging into the main sewer.    ii) Soak pits in permeable ground. iii) Surface water drains connected to main sewer through a sediment chamber. iv) They are less hygienic as they are open and exposed to atmosphere. v) They should be laid at a gradient / slope for easy flow.

Sanitary Fittings and accessories:

These are appliances used in a hotel building plumbing system to receive human excreta and waste water from bathrooms, kitchens of the buildings.

Water Closet: (WC)  (Also called Flush Toilet) This is a water flushed plumbing system fixture designed to receive the human excreta directly and is connected to the soil pipe by means of a Trap. (Trap is a downward looped section of pipe of U-shape, in the lower part of which remains a quantity of water, acting as a seal for foul smelling gas).

A flush toilet is a toilet that disposes of human waste by using water to flush it through a drainpipe to another location. Flushing mechanisms are found more often on western toilets (used in the sitting position), but many squat toilets also are made for automated flushing. Modern toilets incorporate an 'S','U', 'J', or 'P' shaped bend that causes the water in the toilet bowl to collect and act as a seal against sewer gases. Since flush toilets are typically not designed to handle waste on site, their drain pipes must be connected to waste conveyance and waste treatment systems. A flush toilet may be euphemistically called a lavatory, a loo, a john or a water closet, abbreviated to "W.C."

 Figure of a Trap

Trap: Because of its shape, the trap retains a small amount of water after the fixture's use. This water in the trap creates a seal that prevents sewer gas from passing from the drain pipes back into the occupied space of the building. Essentially all plumbing fixtures including sinks, bathtubs, and toilets must be equipped with either an internal or external trap.

Flushing Cisterns: The flushing cistern of a water closet is a device which releases a fixed quantity of water under pressure so as to flush and clean the pan and trap of the toilet. There are two types of flushing cisterns: a) High Level Cistern : Made of cast iron minimum height 2.25 mtr. Bell Type. Now a days made of plastic / PVC with fibre glass reinforcement for greater strength. These are operated by pulling action of chain. The discharge capacities are 5, 10 & 15 litres. They should discharge at an average rate of 5 litres in 3 secs.  b) Bell Type cisterns: These are siphonic types consisting of a C.I. tank of 10 to 15 litres, provided with a central outlet stand pipe covered by bell shaped C.I. vessel. This bell is connected to a chain through a lever arm arrangement. When the chain is pulled the bell receives a jerk and splashes some water down the central pipe. This water takes some air alongwith it and a partial vacuum is created at the top of the bell (at its crown). This starts the siphonic action and all water inside the cistern is sucked rapidly through the large opening at the base of the bell. The emptying action takes only a few seconds causing a powerful flush in the water closet. This cistern is supplied with water through a float ball valve arrangement so that the water inlet closes when the cistern is full.