📘 Important for GNM/BSc Nursing, NHM, NORCET, AIIMS, GPSC, and Community Health Nursing Exams
Water-borne diseases are illnesses caused by microorganisms (like bacteria, viruses, protozoa) which are transmitted through contaminated water.
👉 They commonly spread due to poor sanitation, unsafe drinking water, and lack of hygiene.
🚱 Drinking untreated water
🚱 Poor sewage disposal
🚱 Open defecation
🚱 Industrial waste in rivers
🚱 Floods and stagnant water
🚱 Lack of water purification
| 💧 Disease | 🔬 Causative Agent | 📋 Key Features |
|---|---|---|
| Cholera | Vibrio cholerae | Profuse watery diarrhea, dehydration |
| Typhoid Fever | Salmonella typhi | High fever, weakness, abdominal pain |
| Hepatitis A & E | Hepatitis A & E viruses | Jaundice, fever, nausea, liver inflammation |
| Giardiasis | Giardia lamblia | Diarrhea, gas, abdominal cramps |
| Amoebiasis | Entamoeba histolytica | Bloody diarrhea, abdominal pain |
| Dysentery | Shigella spp. | Mucus and blood in stool |
| Cryptosporidiosis | Cryptosporidium parvum | Watery diarrhea, especially in immunocompromised |
| Poliomyelitis | Poliovirus | Fever, paralysis (in severe cases) |
⚠️ Diarrhea or dysentery
⚠️ Vomiting and nausea
⚠️ Abdominal pain and cramps
⚠️ Fever and chills
⚠️ Weakness and fatigue
⚠️ Jaundice (in Hepatitis A/E)
⚠️ Dehydration (especially in children)
✔️ Boil or filter drinking water
✔️ Use chlorinated or treated water
✔️ Promote handwashing and hygiene
✔️ Prevent open defecation (use of toilets)
✔️ Proper sewage and waste disposal
✔️ Health education and awareness
✔️ Immunization (Typhoid, Hepatitis A, Polio)
✔️ Monitor water quality regularly
✔️ Community-based interventions during floods
🩺 Oral Rehydration Solution (ORS) – for dehydration
💊 Antibiotics – for bacterial infections (e.g., typhoid, cholera)
💊 Antiprotozoals – for amoebiasis, giardiasis
💊 Supportive care – rest, fluids, nutrition
💉 Vaccines – Typhoid, Polio, Hepatitis A
🟨 Cholera is caused by Vibrio cholerae and spreads via contaminated water
🟨 Typhoid is caused by Salmonella typhi and shows step-ladder fever
🟨 Hepatitis A/E are viral water-borne diseases causing jaundice
🟨 ORS is the first line treatment for dehydration due to diarrhea
🟨 Boiling water kills most pathogens and prevents water-borne illnesses
Q1. Which of the following is a bacterial water-borne disease?
🅰️ Hepatitis A
🅱️ Polio
✅ 🅲️ Typhoid
🅳️ Giardiasis
Q2. What is the causative agent of Cholera?
🅰️ Salmonella
✅ 🅱️ Vibrio cholerae
🅲️ Shigella
🅳️ Hepatitis virus
Q3. Which water-borne disease affects the liver and causes jaundice?
🅰️ Cholera
✅ 🅱️ Hepatitis A
🅲️ Dysentery
🅳️ Giardiasis
Q4. What is the primary method to prevent water-borne diseases?
🅰️ Eating packaged food
✅ 🅱️ Drinking boiled or purified water
🅲️ Wearing masks
🅳️ Avoiding vaccines
Q5. Which organism causes Amoebic dysentery?
🅰️ Giardia
✅ 🅱️ Entamoeba histolytica
🅲️ Vibrio cholerae
🅳️ Hepatitis E virus
📘 Important for GNM/BSc Nursing, NHM, NORCET, AIIMS, GPSC, and Community Health Nursing Exams
Slow Sand Filtration (SSF) is a biological method of purifying water at a large scale. It removes suspended particles, bacteria, and pathogens by slowly passing water through a bed of fine sand.
👉 It is highly effective, low-cost, and suitable for rural and small urban areas.
✔️ Remove physical impurities
✔️ Remove microorganisms (e.g., bacteria, protozoa)
✔️ Produce safe, clear, and odorless drinking water
✔️ Provide low-maintenance, sustainable filtration
| 🧩 Layer | 📝 Function |
|---|---|
| Supernatant (raw water) | Settles larger particles by gravity |
| Schmutzdecke (biological layer) | Vital zone formed by algae, bacteria, protozoa; kills pathogens |
| Fine sand layer | Main filtering medium – removes suspended matter |
| Gravel layers | Support sand and allow filtered water to collect |
| Underdrain system | Collects and transports purified water |
Water flows slowly (0.1–0.4 m/hour) through the biological layer (Schmutzdecke) and sand bed.
⏳ The biological activity and physical filtration together remove bacteria, viruses, turbidity, and organic matter.
🟢 A biological layer formed on the surface of sand
🟢 Composed of algae, bacteria, fungi, protozoa
🟢 Takes 5–10 days to form
🟢 Major role in pathogen removal
🟢 Needs regular cleaning once clogged
🔁 When flow rate reduces:
✔️ Top 1–2 cm sand is scraped off
✔️ Schmutzdecke reforms in 1–2 weeks
✔️ Filter resumes operation after resting period
✅ Removes 99% bacteria
✅ No chemicals required
✅ Low cost and eco-friendly
✅ Simple to operate and maintain
✅ Suitable for village and semi-urban use
❌ Requires large land area
❌ Slow rate of filtration
❌ Schmutzdecke takes days to develop
❌ Not suitable for water with heavy turbidity
🟨 SSF works at 0.1–0.4 m/hr flow rate
🟨 Schmutzdecke is the biological layer responsible for pathogen removal
🟨 SSF requires no chemicals for purification
🟨 SSF is ideal for rural water supply schemes
🟨 Sand bed is cleaned by scraping the top layer
Q1. What is the main filtering medium in SSF?
🅰️ Gravel
✅ 🅱️ Fine sand
🅲️ Charcoal
🅳️ Cotton
Q2. What is Schmutzdecke?
🅰️ Drainage pipe
✅ 🅱️ Biological layer on sand
🅲️ Chemical used in water
🅳️ Mechanical scrubber
Q3. How is the slow sand filter cleaned?
🅰️ Flushing with water
✅ 🅱️ Scraping the top sand layer
🅲️ Boiling the sand
🅳️ Adding chlorine
Q4. Which is a major disadvantage of SSF?
🅰️ It kills bacteria
🅱️ Requires no chemicals
✅ 🅲️ Needs large space and is slow
🅳️ Suitable for villages
Q5. What is the ideal flow rate in SSF?
🅰️ 1–2 m/hr
✅ 🅱️ 0.1–0.4 m/hr
🅲️ 5–10 m/hr
🅳️ 0.01 m/hr
📘 Important for GNM/BSc Nursing, NHM, AIIMS, NORCET, GPSC, and Community Health Nursing Exams
Rapid Sand Filtration (RSF) is a mechanical method of water purification used in large-scale water treatment plants.
It involves passing water rapidly through sand to remove suspended solids and pathogens, usually after coagulation and sedimentation.
👉 RSF is faster and more efficient than Slow Sand Filtration, especially for urban and industrial needs.
✔️ Purify large quantities of water quickly
✔️ Remove turbidity, suspended solids, and microorganisms
✔️ Supply clear, potable water for cities and towns
✔️ Support public health and prevent water-borne diseases
| 🧩 Layer/Unit | 📝 Function |
|---|---|
| Inlet chamber | Receives raw water after sedimentation |
| Coarse gravel layer | Supports sand and improves drainage |
| Fine sand layer | Main filtering medium to trap particles |
| Underdrain system | Collects filtered water and allows air backwash |
| Wash water troughs | Collect dirty water during backwashing |
🌀 Water passes quickly (5–15 m³/hr/m²) through the sand bed
🧪 Prior coagulation and sedimentation are necessary
🩺 Removes suspended particles, some bacteria, and improves clarity
🌪️ Uses backwashing for cleaning the filter media
🧼 Backwashing = Cleaning the sand by reversing water flow + air
🔁 Performed every 24–48 hours or when filter gets clogged
⏳ Takes about 15–20 minutes
📌 Important to maintain efficiency and prevent contamination
| 🔍 Feature | 🧴 RSF | 🏖️ SSF |
|---|---|---|
| Flow Rate | Fast (5–15 m³/hr/m²) | Slow (0.1–0.4 m³/hr/m²) |
| Area Required | Less | More |
| Cleaning Method | Backwashing | Scraping |
| Cost | Higher | Lower |
| Use | Urban areas | Rural areas |
| Biological Layer | Absent | Present (Schmutzdecke) |
🔹 High-speed filtration
🔹 Suitable for large populations
🔹 Needs less space
🔹 Automated and efficient
🔹 Consistent water quality when properly maintained
❌ Expensive setup
❌ Needs electricity and skilled personnel
❌ Less effective in removing bacteria compared to SSF
❌ Needs frequent backwashing
🟨 RSF filters water quickly with help of coagulation
🟨 Backwashing is used to clean the sand bed in RSF
🟨 RSF is ideal for urban and municipal water supply
🟨 No Schmutzdecke layer is formed in RSF
🟨 Flow rate of RSF = 5–15 m³/hour/m²
Q1. What is the typical flow rate in Rapid Sand Filtration?
🅰️ 0.1–0.4 m³/hr/m²
✅ 🅱️ 5–15 m³/hr/m²
🅲️ 50–60 m³/hr/m²
🅳️ 1 m³/hr/m²
Q2. Which method is used to clean RSF?
🅰️ Scraping
🅱️ Bleaching
✅ 🅲️ Backwashing
🅳️ Filtration
Q3. Which of the following is not true about RSF?
🅰️ Requires coagulation and sedimentation
🅱️ Used in urban areas
🅲️ Forms biological layer
✅ 🅲️ Forms biological layer (False)
Q4. What is the main function of the sand layer in RSF?
🅰️ Store water
✅ 🅱️ Trap impurities
🅲️ Add chemicals
🅳️ Filter air
Q5. What is the disadvantage of RSF?
🅰️ Quick process
✅ 🅱️ High cost and maintenance
🅲️ Low turbidity removal
🅳️ Suitable for rural areas
📘 Important for GNM/BSc Nursing, NHM, AIIMS, NORCET, GPSC & Community Health Nursing Exams
Small-scale water purification refers to the domestic or community-level techniques used to make unsafe water safe for drinking, especially in rural homes or emergency settings.
👉 It is essential in preventing water-borne diseases where municipal supply is absent or unreliable.
✔️ Remove impurities, germs, and turbidity
✔️ Make water safe and palatable
✔️ Provide emergency drinking water
✔️ Prevent diarrhea, typhoid, cholera, hepatitis A/E
🔥 Boil water for 10–15 minutes
✅ Kills all bacteria, viruses, parasites
✅ Simple, effective
❌ Does not remove chemical contaminants
🧴 Pass water through cloth, sand, or commercial filters
✅ Removes visible dirt and some microbes
✅ Types: Candle filters, gravity filters, biosand filters
❌ May not kill all pathogens
🏞️ Let water stand undisturbed for 2–3 hours
✅ Heavy particles settle at bottom
✅ Useful as a pre-treatment step
❌ Does not remove microbes
🧂 Add bleaching powder or chlorine tablets
✅ Kills bacteria, viruses
✅ Inexpensive and effective
💡 1 gm bleaching powder treats 1000 liters of water
❌ Unpleasant taste if overdosed
🌞 Place water in transparent PET bottles and expose to sunlight for 6–8 hours
✅ UV rays and heat kill microbes
✅ Eco-friendly, cost-effective
❌ Needs full sun and clear water
🧪 Add alum (aluminum sulfate) and stir
✅ Settles down suspended impurities
✅ Used before filtration
❌ Does not kill germs
💊 Used for emergency or travel purposes
✅ Kills most bacteria and viruses
❌ May leave a taste and smell
🥉 Store water in a clean copper vessel for 8–10 hours
✅ Natural antimicrobial properties
✅ Improves taste and digestion
❌ Less effective in very contaminated water
👩⚕️ Educate community about boiling and filtering
👩⚕️ Demonstrate chlorination technique
👩⚕️ Encourage clean storage of water
👩⚕️ Monitor water sources in villages and slums
👩⚕️ Report outbreaks of water-borne diseases
🟨 Boiling kills most germs but not chemicals
🟨 1 gram bleaching powder disinfects 1000 L water
🟨 Alum is used to settle suspended particles
🟨 SODIS uses sunlight + PET bottles to kill pathogens
🟨 Sand filters are used in home and community water units
Q1. Which method kills all microorganisms effectively at home?
🅰️ Sedimentation
🅱️ Filtration
✅ 🅲️ Boiling
🅳️ Alum use
Q2. How much bleaching powder is needed to disinfect 1000 L water?
🅰️ 10 gm
✅ 🅱️ 1 gm
🅲️ 0.1 gm
🅳️ 100 gm
Q3. What is the function of alum in water purification?
🅰️ Kill viruses
✅ 🅱️ Settle suspended particles
🅲️ Remove chlorine
🅳️ Add minerals
Q4. What is SODIS?
🅰️ Sand filtration method
✅ 🅱️ Solar disinfection using sunlight
🅲️ Boiling water with salt
🅳️ Adding iodine drops
Q5. Which of the following is a biological water purifier?
🅰️ Candle filter
🅱️ Alum
✅ 🅲️ Copper pot
🅳️ Iodine
📘 Essential for GNM/BSc Nursing, NHM, NORCET, AIIMS, GPSC & Community Health Nursing Exams
Water quality testing involves evaluating water to determine if it is safe for human consumption.
Safe water must be free from harmful bacteria, viruses, chemicals, and physical contaminants.
👉 Testing is done using physical, chemical, and bacteriological methods.
| 🔍 Test Type | ⚙️ What It Detects |
|---|---|
| Physical Tests | Color, taste, odor, turbidity, temperature |
| Chemical Tests | pH, hardness, nitrates, fluoride, chlorine |
| Bacteriological Tests | Coliform bacteria, E. coli presence |
| Biological Tests | Presence of plankton, parasites, algae |
👁️ Observe color, smell, turbidity, and taste
✅ Indicates visible contamination
❌ Cannot confirm microbial safety
🧴 Uses turbidity meter or turbidity tube
✅ Measures cloudiness due to suspended solids
💡 Safe drinking water should be <5 NTU
🧪 Uses pH strips or digital meter
✅ Ideal drinking water pH = 6.5 – 8.5
💧 Checks leftover chlorine in water
✅ Use Orthotolidine test or DPD reagent test
✅ Minimum 0.5 mg/L residual chlorine should be present
🔹 Detects levels of:
🦠 Detects coliform bacteria, especially E. coli
🔬 Use:
🧪 Portable H2S strip test or chloroscope
✅ Quick detection of bacterial contamination
✅ Useful in villages, emergencies, and schools
🐠 Presence of mosquito larvae, algae blooms
✅ Indicates stagnant or polluted water
👩⚕️ Collect water samples properly
👩⚕️ Conduct basic field tests (pH, chlorine)
👩⚕️ Report unsafe water immediately
👩⚕️ Educate community on signs of unsafe water
👩⚕️ Promote safe storage and handling practices
🟨 Safe pH range for drinking water is 6.5–8.5
🟨 Residual chlorine should be 0.5 mg/L
🟨 Coliform test is the gold standard for bacteriological safety
🟨 Turbidity should be <5 NTU for potable water
🟨 H₂S test is a quick field method for bacterial contamination
Q1. Which test is used to detect coliform bacteria in water?
🅰️ Turbidity test
✅ 🅱️ Multiple tube fermentation test
🅲️ pH test
🅳️ Chlorine test
Q2. What should be the ideal pH of drinking water?
🅰️ 4–6
✅ 🅱️ 6.5–8.5
🅲️ 8.5–9.5
🅳️ 3–5
Q3. What is the minimum safe residual chlorine level in water?
🅰️ 1.5 mg/L
🅱️ 0.2 mg/L
✅ 🅲️ 0.5 mg/L
🅳️ 2 mg/L
Q4. H₂S strip test is used for detecting:
🅰️ Arsenic
🅱️ Fluoride
✅ 🅲️ Bacterial contamination
🅳️ Iron
Q5. Which physical property is checked with turbidity tube?
🅰️ Color
✅ 🅱️ Suspended particles
🅲️ Acidity
🅳️ pH
📘 Vital for GNM/BSc Nursing, NHM, NORCET, AIIMS, GPSC & Community Health Nursing Exams
🧪 Purpose:
To detect the presence of residual chlorine in drinking water.
Orthotolidine reacts with free chlorine in water to form a yellow-colored compound.
| 🌈 Color | 📋 Chlorine Level |
|---|---|
| No color change | No chlorine present (unsafe) |
| Pale yellow | < 0.1 mg/L (inadequate) |
| Bright yellow | ~0.5 mg/L (adequate) |
| Deep yellow-orange | >1.0 mg/L (too much chlorine) |
❌ Cannot differentiate free and combined chlorine
❌ Not very accurate – replaced by DPD test
💊 DPD = Diethyl Para Phenylene Diamine
🧪 Purpose: To estimate free and total residual chlorine in water.
| 🌸 Color | 💧 Free Chlorine Level |
|---|---|
| No color | 0 mg/L (unsafe) |
| Light pink | 0.1–0.2 mg/L (low) |
| Rose pink | 0.5 mg/L (adequate) |
| Deep pink | >1.0 mg/L (excess) |
✅ Most accurate method used today by water supply boards and health workers.
🧰 Purpose:
To estimate the exact quantity of bleaching powder needed to disinfect 1000 liters of water.
👩⚕️ Use field kits for testing residual chlorine
👩⚕️ Educate community on safe chlorination
👩⚕️ Monitor rural water supply safety
👩⚕️ Participate in water surveillance programs
🟨 Orthotolidine test gives yellow color with chlorine
🟨 DPD test gives pink color – more accurate for chlorine detection
🟨 Horrock’s Apparatus tells how much bleaching powder to use
🟨 Minimum safe residual chlorine = 0.5 mg/L
Q1. Which test gives a pink color in presence of free chlorine?
🅰️ Orthotolidine
✅ 🅱️ DPD
🅲️ Horrock’s
🅳️ Turbidity
Q2. What is the use of Horrock’s Apparatus?
🅰️ Filter water
🅱️ Check pH
✅ 🅲️ Estimate bleaching powder dose
🅳️ Detect turbidity
Q3. What is the minimum residual chlorine needed in drinking water?
🅰️ 1 mg/L
🅱️ 0.1 mg/L
✅ 🅲️ 0.5 mg/L
🅳️ 2.0 mg/L
Q4. What is the limitation of orthotolidine test?
🅰️ Very accurate
🅱️ Differentiates chlorine types
✅ 🅲️ Cannot differentiate free and combined chlorine
🅳️ Easy for field use
Q5. In DPD test, what does deep pink indicate?
🅰️ No chlorine
🅱️ Adequate level
✅ 🅲️ Excess chlorine
🅳️ Contaminated water
📘 Important for GNM/BSc Nursing, NHM, AIIMS, NORCET, GPSC, and Community Health Nursing Exams
Chemical testing of water refers to detecting the presence and level of chemicals and minerals that may affect health or water safety.
👉 These tests ensure the water is non-toxic, non-corrosive, and fit for human consumption.
✔️ Ensure safe levels of minerals and salts
✔️ Detect toxic substances (e.g., arsenic, lead)
✔️ Identify pollution sources
✔️ Assess water’s corrosiveness or scaling effect
✔️ Monitor compliance with WHO/BIS standards
| 💧 Parameter | ⚠️ Acceptable Limit (as per BIS/WHO) | 🔬 Health Effect if Exceeded |
|---|---|---|
| pH | 6.5 – 8.5 | Too acidic or basic water irritates GI tract |
| Turbidity | < 5 NTU | Cloudiness reduces disinfection |
| Total Hardness | < 200 mg/L | Scaling in pipes, bad taste |
| Total Dissolved Solids (TDS) | < 500 mg/L | Salty taste, kidney issues |
| Nitrates | < 45 mg/L | Blue baby syndrome in infants |
| Chloride | < 250 mg/L | Salty taste, corrosion |
| Fluoride | 0.7–1.2 mg/L | Dental/skeletal fluorosis if high |
| Iron | < 0.3 mg/L | Metallic taste, stains utensils |
| Arsenic | < 0.01 mg/L | Skin cancer, neurological issues |
| Lead | < 0.01 mg/L | Brain damage, anemia |
| Sulphate | < 200 mg/L | Diarrhea in high concentration |
| Free Chlorine | 0.2–0.5 mg/L | Needed for disinfection, excess causes taste issues |
🧪 Colorimetric Methods (e.g., DPD for chlorine)
⚖️ Titration methods (e.g., EDTA titration for hardness)
🔬 Spectrophotometry (e.g., fluoride, nitrate)
💊 Test kits (field-based, rapid testing)
🧴 Digital meters (TDS, pH, conductivity)
👩⚕️ Collect water samples using sterile techniques
👩⚕️ Ensure proper labeling and storage of samples
👩⚕️ Interpret basic field test results (pH, chlorine, TDS)
👩⚕️ Refer abnormal results to higher authorities
👩⚕️ Educate public on avoiding chemical contamination sources
🟨 Nitrate >45 mg/L = risk of blue baby syndrome
🟨 Arsenic in water can cause skin cancer
🟨 Safe fluoride = 0.7–1.2 mg/L
🟨 High TDS = salty taste and kidney burden
🟨 EDTA titration is used to detect water hardness
Q1. Which chemical in drinking water causes blue baby syndrome?
🅰️ Fluoride
✅ 🅱️ Nitrate
🅲️ Sulphate
🅳️ Chloride
Q2. What is the safe limit of fluoride in drinking water?
🅰️ 0.2–0.4 mg/L
✅ 🅱️ 0.7–1.2 mg/L
🅲️ 2–3 mg/L
🅳️ 5–6 mg/L
Q3. What is the acceptable pH range for drinking water?
🅰️ 4–6
✅ 🅱️ 6.5–8.5
🅲️ 9–10
🅳️ 5–5.5
Q4. Arsenic in water is harmful because it causes:
🅰️ Dental caries
🅱️ Bone deformity
✅ 🅲️ Skin and internal cancers
🅳️ Anemia only
Q5. EDTA titration is used to test:
🅰️ Fluoride
🅱️ Chlorine
✅ 🅲️ Hardness
🅳️ Nitrate