Health And Safety Of Rainwater Harvesting

HEALTH AND SAFETY OF RAINWATER HARVESTING by : ENGR. REX L. LABADIA Department of Health Center for Health Development Davao Region

WATER CYCLE

Rainwater and Its Impurities

Group I – Atmospheric Gases

Group II – Solid Atmospheric Impurities

Atmospheric Gases

Oxygen

- O 2 dissolved in water is essential to the palatability of drinking water

- its absence is reason for flat and insipid taste of boiled or distilled water

Atmospheric Gases

2 . Nitrogen

- N 2 is approximately 78% in the

atmosphere while O 2 is 21%. But N 2

dissolved is about double that 0 2 .

Atmospheric Gases

3. Carbon Dioxide

- CO 2 dissolved causes solution of further

mineral impurities from earth’s crust

Atmospheric Gases

4. Ozone

- formed by electrical discharge

- also formed by action of ultra-violet rays

on car exhaust fumes

Atmospheric Gases

5. Oxides of Nitrogen

- formed by electrical discharge, generally

nitrous oxide and nitric oxide

Atmospheric Gases

6. Ammonia

- the product of organic decomposition

- returned to earth as ammonium salts, ie,

carbonates, nitrates, sulfates or chlorides

Atmospheric Gases

7. Sulfur, sulfuretted hydrogen and oxides of sulfur

- from natural sources such as volcanoes,

oceans, and decaying matters

- also formed by fossil fuel combustion

Atmospheric Gases

8. Hydrogen Peroxide

- from electrical discharges

Atmospheric Gases

The overall effect of these gases is to make rainwater acidic . This makes the rainwater aggressive, easily dissolving some materials such as metal works. It can cause destruction of buildings in which limestone and marble are used.

Solid Atmospheric Impurities

Silica

Iron Oxide

Calcium Carbonate

Sodium Chloride

Ammonium Chloride

Solid Atmospheric Impurities

Magnesium Sulfate

Carbon – soot, etc.

Organic Matter

Micro-organisms such as bacteria and wind-borne spores

The two most important solid atmospheric impurities are organic matter and micro-organisms. In many instances, they make rainwater entering a cistern unsafe for drinking.

Impurities such as decaying vegetation, bird droppings and chemical residues may also go with the rainwater from the roofs of buildings, gutters and pipes before it enters the cistern.

In harvesting rainwater for drinking, care should be taken to avoid materials or coatings for roofing, drains and pipes that can dissolve to give high concentrations in water. Elevated levels of zinc and lead in harvested rainwater have been reported.

Some Materials Suitable for Roof Surfaces and Drain Pipes:

Steel

Plastic

Aluminum

Fiberglas

Asbestos roof and oil-based bitumen shingles should be avoided. Lead flushing should never be used.

Suitable Materials for Storage Cisterns:

Reinforced Concrete

Fiberglass/polyethelene

Stainless Steel

Clay/ceramics

Diseases that may be acquired by drinking contaminated rainwater:

Microbic – caused by specific organisms

Examples : typhoid fever, bacillary dysentery, cholera, poliomyelitis, infectious

hepatitis, amoebic dysentery

Non-microbic – caused by excess of certain

substances in water

Examples : lead poisoning, nitrate poisoning

Drinking rainwater is not advised where potable water supplies exist, particularly in urban areas where rainwater can contain higher contaminant levels.

If harvested rainwater is used for drinking, it must be regularly examined for physical, chemical and bacteriological quality. 1. Physical and chemical examination– at least once a year 2. Bacteriological examination – at least once in 3 months

In areas where there are no sources of potable water supply, rainwater contaminated with undesirable microorganisms may be rendered safe for drinking by applying appropriate disinfection procedures.

Some Household Water Disinfection Methods:

1. Thermal and Solar Disinfection

- Boiling for at least two minutes

- SODIS (solar disinfection)

2. Chemical Disinfection

- Chlorine compounds

- Hyposol

- Aquatabs

What is SODIS Stands for Solar Water Disinfection 1. 2. SODIS is a household water treatment method to provide safe drinking water SODIS utilizes the synergy of the UV-A radiation and temperature gain to inactivate the micro-organism in the water

SODIS is ... SODIS can be applied anywhere where sunshine is available SODIS can be done by all members of the family SODIS is simple, easy methodology to have safe drinking water for the family SODIS utilizes solar energy to improve water quality by killing the bacteria in the water

S un S hine PET P lastic Bottles O pen s pace w hat is n eeded to do SODIS

Yayasan Dian Desa Can be divided into three different kinds : Ultra Violet Radiation ( it cannot be seen but can destroy living cell – e.g. our skin will be destroyed when we stayed too long in the sun Sun light Infra red radiation (it cannot be seen but we can feel the heat - micro organism is sensitive to heat) S olar R adiation

synergy Yayasan Dian Desa Water in the container gain temperature from the infra red radiation and also the Ultra violet radiation penetrates into the water in the container --- they synergize to kill the bacteria in the water That is why in SODIS the container has to be transparent so that the UV radiation can penetrate through the bottles into the water How does SODIS work

1 3 2 Fill with the raw water for treatment Expose to sunshine in clear area, make sure that the place will not be shaded How to do SODIS ??? Prepare 1.5 liters PET plastic bottles, and wash them using soft materials in order not to scratch the bottles

Every one in the family can do SODIS and drink SODIS water – A Healthy and Happy family 4 5 The synergy of the UV-A radiation and temperature from the sun will kill the bacteria in the water ---- the water is safe to drink

Duration of exposure :

Expose to sunshine from 6 or 7 in the morning to 5 in the afternoon

If there is intermittent rain expose the bottles for two days (you can let the bottles in the rain)

SODIS L imitations Cannot be applied with large containers 1 2 Cannot be applied if the water is turbid Can only inactivate microorganism , not change others such as chemical substances, smell, or salinity 3

Research on the material Can PET bottles be used for SODIS without concern or do possibly leaking substances pose adverse health effects?

1. Study at the EAWAG about photooxidation of the bottles in 2000:

-> Photoproducts are formed at the outer side of the bottle.

-> There is no diffusion of Formaldehyde or Acetaldehyde into the water

2. Study in collaboration with the EMPA (Swiss Federal Institute for Materials Testing) 2003 on the diffusion of Phtalates and Adipates:

- max. conc. of carcinogenic substances (DEHA, DEHP) is much lower than WHO guidelines for drinking water

How to use chlorine compounds with large chlorine content (60% to 75% available chlorine):

Step I – Prepare a stock solution using one

(1) level teaspoonful of the powder

to one (1) liter of water.

How to use chlorine compounds with large chlorine content (60% to 75% available chlorine):

Step II - Mix two (2) teaspoons stock solution

to five (5) gallons (or 20 liters) of

water. Let the disinfected water stand

for at least thirty (30) minutes before

using.

Note : Keep stock solution away from sunlight.

Discard if unused after one (1) week and

replace with freshly prepared one.

BRINGING CLOSER ACCESS TO SAFE DRINKING WATER IN EVERY HOME

What is the HFSW

Point- of- use (POU) treatment of

- raw or

- contaminated

using Low strength Sodium Hypochlorite Solution (HYPOSOL), 1.25%

Storage of the treated water :

- plastic containers

- narrow mouthed

- lidded, with faucet

to prevent re-contamination

S imple to use:

Fill 20-liter plastic container with water. If water is turbid, filter it with clean cloth.

Open sealed bottle of HYPOSOL

Pour required amount of HYPOSOL to raw water.

Close water container, shake well and wait for 30 minutes.

Aerate for 10-15 minutes

Water is safe and ready to drink for both young and adults.

Affordable :

100 ml HYPOSOL:

costs P70.00 (Davao Price)

can disinfect 28 gerrycans

(5-gallon or 20-liter water)

good for one to one and

one-half months use of

drinking water by one household

Manufactured by: LONG LIVE PHARMA

Poblacion, Sta. Barbara, Pangasinan

Tel. No. 075-515-3048

NaDCC (Chlorine) Tablets

Aquatabs ® Composition

Biocide: sodium dichloroisocyanurate (organic chlorine donor)

Also known as sodium troclosene, sodium dichloro-s-triazine trione (NaDCC)

Use one (1) tablet for every twenty (20) liters of clear water

If water looks dirty, filter it and use two (2) tablets

How to Protect Harvested Rainwater:

Cover and thoroughly screen tanks to exclude mosquitoes, birds and animals. Install a filter.

Install a first flush diverter to prevent the initial flow of rain entering the tank.

Desludge tank periodically with a tap installed at its base.

How to protect Harvested Rainwater:

Protect water in tanks from sunlight, which can stimulate algal growth. Plastic tanks may allow light to penetrate so they should be kept out of the sun or painted

Have a VISION DREAM big! Focus on the POSITIVE…… There’s always something better !