Hand Dug Water Well Sanitation

Common Contaminants in Dug Wells

The US EPA has listed the most-common contaminants found in shallow or hand-dug wells:

1. Microbiological contaminants:
   
   eColi, coliform, or other bacteria, viruses, and parasites common in surface runoff and in shallow groundwater,
   
   risking gastrointestinal illness & serious infections.
   
   Also see BACTERIA LEVELS in WATER, INTERPRETATION for water test results.
2. Nitrates & nitrites:
   
   common especially where farming is nearby or where fertilizers have been used - risking methemoglobinemia or "blue baby syndrome". .
   
   Infants below six months who drink water with high levels of nitrate can become seriously ill and die.
3. Heavy metals
   
   such as arsenic, antimony, cadmium, chromium, copper, lead, selenium & others, risking acute and chronic toxicity, liver, kidney, and intestinal damage, anemia, and cancer.
4. Organic chemicals - in inks, dyes, pesticides, paints, pharmaceuticals, solvents, petroleum products, sealants, and disinfectants.
   
   Organic chemicals can enter ground water and contaminate private wells through waste disposal, spills, and surface water run-off - risking damage to their kidneys, liver, circulatory system, nervous system, and reproductive system.
5. Radionuclides -
   
   radioactive forms of elements such as uranium and radium.
   
   Radionuclides ... contaminate private wells through groundwater flow, waste water seepage and flooding - causing toxic kidney effects and increased risk of cancer.
6. Fluorides -
   
   excessive consumption of fluoride can cause skeletal fluorosis, a condition characterized by pain and tenderness of bones and joints

- (US EPA 2020)

More about this problem is

at DUG WELL POTABILITY TEST

Our photo above illustrates a hand dug well that was later converted to a drilled well with a steel casing. The old well pit is functioning now as a well pit.

We noticed that there down in the "pit" formed by the original dug well there is still no protection against surface runoff entering the top of the well casing - a sanitary or water potability concern.

This rural well is being used for crop watering in San Miguel de Allende.

A dug well that gave sanitary drinking water a hundred years ago may be at greater risk of contamination today as more chemicals contaminate both surface runoff and groundwater. And it's hard to keep contaminants out of a dug well.

OPINION: While 100 years ago or more surface water found in dug wells and springs was often of high quality and potable - at least in some areas of the world.

But today it is very difficult to find sanitary drinking water where surface runoff and shallow subsurface water enter the water supply such as that provided by a dug well.

This is also true for other types shallow wells such as

DRIVEN POINTWELLS,

and even drilled wells protected by a well casing in some cases.

See WATER TESTING GUIDE

and WATER CONTAMINANT LEVELS & LIMITS for advice.

See WATER TREATMENT EQUIPMENT CHOICES for some options to help assure that water from a dug well is sanitary and thus acceptable for drinking.

Also see the EPA GUIDE to WATER QUALITY.

Algae Problems in Dug Well Water

How do we get rid of algae in our dug well?

We have a hand dug well we did for our cows and the water runs down to tank for cows. The problem were having is algae will plug the line and stop the water flow and we have to plow the line out,

I'm wondering if there's any way to get rid of the algae On 2018-10-03 by Melissa

Answer by (mod) - Explanation, Suggestions, & Warnings about disinfecting water in a dug well to get rid of algae

Bottom line: To get rid of algae in the dug well that supplies water to your livestock you'll need to empty and clean the well and the pipe, including a disinfecting step. In fact you may need to empty the well, remove any debris, silt, etc., then disinfect its surfaces a second time, then allow the well to re-fill.

And once the well is cleaned you'll need to protect it from surface runoff and to provide a safe cover over the well opening.

Slime is clogging our dug well water filter - what causes it?

The water from our dug well contains clear slime that's clogging our water filter. What is it and what is causing it and what can be done to get read of it ? On 2011-07-06 by Ron Saltzman

Explanation by (mod) -

"Slime" in drinking water is usually an algae growth; sounds like you need a chlorination system and you need to shock the well - to sanitize it; I'd ask a local water test company to inspect and test the system.

See my comments above for Melissa,

Then follow the procedures we detail just below at DUG WELL CLEANING & DUG WELL DISINFECTION

How to Clean Out & Disinfect a Dug Well

Rather than repeat what other experts have already tested and written, we urge our readers who need to clean out a dirty or contaminated hand dug well to read the OXFAM and WHO documents listed next.

We follow these references with tables giving guidance on the amount of household chlorine bleach to use to disinfect a well.

• OXFAM, REPAIRING, CLEANING AND DISINFECTING HAND DUG WELLS (Website) (2012) (OxfamWASH.org is created by the WASH team, a part of Oxfam’s Global Humanitarian Team.) Local backup copy saved as Repair-Clean-Disinfect-Hand-Dug-Wells-OXFAM.pdf [Oxfam is an international confederation of 21 independent non-governmental organizations (NGOs), focusing on the alleviation of global poverty, founded in 1942] - Wikipedia
  
  Abstract:
  

  Hand dug wells may need repairing, cleaning and disinfecting after inundation by flood water, inundation of seawater as in the case of a tsunami, materials entering as the result of mudslides or as a result of hurricanes, or simply after long periods of limited maintenance or neglect.
  
  If work has been undertaken on the well to try to increase its yield through, widening or lining the well, then cleaning and / or disinfection will also be appropriate.

  This Technical Brief identifies the process for repairing, cleaning and disinfecting hand dug wells and also discusses the OXFAM kits which can be used for these processes.

• WHO, CLEANING HAND-DUG WELLS Technical Notes on Drinking-Water, Sanitation and Hygiene in Emergencies [PDF] (2013) (Canadian WHO International website), World Health Organization WEDC, Authors: Sam Godfrey and Bob Reed. Water, Engineering and Development Centre Loughborough University Leicestershire LE11 3TU UK T: +44 1509 222885 F: +44 1509 211079 E: wedc@lboro.ac.uk W: http://wedc.lboro.ac.uk - local backup copy saved offlline as Cleaning-Hand-Dug-Wells-WHO.pdf

The authors note that after cleaning and repairing the well and piping you'll need to measure both turbidity and pH levels of water to determine if chlorination is even effective in your particular well.

The authors warn:

Never chlorinate turbid water because suspended particles can protect micro-organisms.

I also recommend this document from the U.S. CDC

• U.S. CDC, DISINFECTING WELLS FOLLOWING AN EMERGENCY [PDF] (Wells County Indiana, USA website), U.S. Centers for Disease Control, local backup copy saved as Emergency-Well-Disinfection-CDC.pdf

How to Sanitize or Disinfect a Dug Well

The U.S. CDC gives guidance on disinfecting wells after an emergency, such as area flooding, that may have contaminated well water.

For a drilled, bored, or dug well the CDC recommends the following:

Drilled OR Dug Well Bleach Disinfection Quantity

Notes to the table above

• Watch out: Use only ordinary unscented household bleach to disinfect wells and well water. You'll see on the product label that the bleach concentration in household bleach will be between 5-9%.
• The bleach concentration target for effective water disinfection is to get a chlorine concentration in the water greater than 100 mg/L of water. That's equal to 0.000133526 ounces per U.S. liquid gallon
• 1 cup = 8 liquid ounces
• 1 US Gallon = 16 cups = 128 liquid ounces
• 1 Liter = 1000 mL or milliliters
• Source: U.S. CDC, HOW TO DISINFECT WELLS AFTER AN EMERGENCY [PDF] (2025) (U.S. CDC Website) U.S. Centers for Disease Control, local backup copy saved Well-Disinfiection-After-Emergency-CDC.pdf
  

Watch out: However reader reports and our own field tests indicate that too often the water available from a hand dug well is contaminated by surface runoff or other nearby contamination sources, so it can be difficult to assure that that water drawn directly from many dug wells is safe to drink without further and continuous treatment by boiling or disinfection.

Therefore in our OPINION, where it's possible to do so, it may make more sense to treat, filter, or sanitize water from a dug well as it is removed.

The procedure for sanitizing water after you have removed it from a well, provided the only concern is bacterial or algae hazards, is at WATER DISINFECTANT QUANTITY or at UV WATER DISINFECTION, PORTABLE

You'll see that to chlorinate the well effectively you'll need to calculate the volume of water in the well.

Watch out: Now the problem is how do we get that bleached water OUT of the dug well so that we can drink the water?

Watch out: You'd need to flush the well by removing water and disposing of it safely until the water no longer has a "bleach" or "chlorine" smell! Details are at CHLORINE HAZARDS in WATER

At WELL CHLORINATION SHOCKING PROCEDURE we explain how to shock or sanitize a drilled or bored well.

More information is at BLEACH DISINFECTANT for DRINKING WATER and at WELL CLEANING PROCEDURES

Disinfect Dug Well Water at Point of Use

Is it useful to disinfect the water in my hand-dug wells?

Thanks for your article about bacteria counts in drinking water. You thought it was pointless to treat a hand dug well

I have two on my property that both have houses and so no direct surface water gets into them. After a rain the one has water seeping into the wall at about seven feet down; the other doesn't have visible water entering in until more like fifteen feet down.

I've had both wells tested and requested coliform counts that the lab said were what you'd expect from spring water. Being under shelter and all do you still think it would be pointless to treat these wells in an attempt to eliminate all coliform? - Anonymous by private email 2020/04/23

Moderator reply: disinfect water at the point of use, not in the well

Photo: a dug well in Campeche, Mexico, photographed through a safety grille installed over the well top.

In my experience and opinion, yes in a sense. There's no advantage to treating just the water that's in any well, but especially a dug well since new water is entering the well whenever any water is removed.

Therefore, even if we treated the water in a dug well and tested it and found it sanitary, there's no assurance that hours later the water is in the same sanitary condition.

See DUG WELL POTABILITY TEST for details.

Contaminants enter the dug well water supply from the surface, from groundwater, and even from defects in the hand pump or electric water pump installation and operation (USDA 1999).

For that reason it makes more sense to install a water treatment system that disinfects all water from the well at the time it is taken out for use in cooking or drinking.

That might be a combination of filter and UV and/or disinfection by chlorine injection.

See details

at WATER TREATMENT EQUIPMENT DISINFECTION

Hand Dug Well Contaminants & Sanitation Guidelines & Research

• BACTERIA LEVELS in WATER, INTERPRETATION
• CHART of WELL WATER CONTAMINANT SOURCES [PDF] U.S. EPA, retrieved 2019/09/18 original source: https://www.epa.gov/privatewells/potential-well-water-contaminants-and-their-impacts
• DUG WELL POTABILITY TEST
• DUG WELL CONSTRUCTION [PDF] U.S. EPA, retrieved 2019/09/18 original source: https://www.epa.gov/sites/production/files/2015-11/documents/dugwell.pdf
  
  Excerpt:
  Dug wells are holes in the ground dug by shovel or backhoe. Historically, a dug well was excavated below the groundwater table until incoming water exceeded the digger’s bailing rate.
  
  The well was then lined (cased) with stones, brick, tile, or other material to prevent collapse. It was covered with a cap of wood, stone, or concrete.
  
  Since it is so difficult to dig beneath the ground water table, dug wells are not very deep.
  
  Typically, they are only 10 to 30 feet deep. Being so shallow, dug wells have the highest risk of becoming contaminated.
  
  To minimize the likelihood of contamination, your dug well should have certain features.
  
  These features help to prevent contaminants from traveling along the outside of the casing or through the casing and into the well.
  
  [Dug well construction features are given in the PDF cited above - Ed.]
• DUG WELL CLEANING, DISINFECTION, SANITATION PROTECTION
• GROUND WATER POLLUTION from SUBSURFACE EXCAVATIONS [PDF] (1973) U.S. EPA, retrieved 2019/09/18 original source: https://nepis.epa.gov
• HAND DUG WELL INSTRUCTION MANUAL [PDF] Henk Holtslag & John deWolf, Foundation Connect International, 2009, web wearch 4/13/12, original source: http://www.connectinternational.nl/files/ST%201.5%20-%20Hand%20dug%20well.pdf,
  
  contact information: Foundation Connect International Jan van Houtkade 50 2311 PE LEIDEN The Netherlands Tel./Fax +31 71 514 1111 Website www.connectinternational.nl Email info@connectinternational.nl
  
  Connect International supports and strengthens local partner organizations in developing countries to facilitate rural communities to achieve the Millennium Development Goals and make an End of Poverty.
• INTERPRETING the LEVEL of BACTERIA in a WATER TEST
• Jegen, Dominika A., et al, "Private Well Water Safety: Practical Counseling Strategies for Primary Care" (NIH National Library of Medicine, PubMed Central Archive Website) - retrieved 2026/08/09
  Abstract Excerpt:
  This article equips family physicians with practical guidance on the reasons and methods of testing private wells for microbiologic and chemical contaminants such as “bacteria, nitrates, arsenic, and lead”. 
• OXFAM, REPAIRING, CLEANING AND DISINFECTING HAND DUG WELLS (Website) (2012) (OxfamWASH.org is created by the WASH team, a part of Oxfam’s Global Humanitarian Team.) Local backup copy saved as Repair-Clean-Disinfect-Hand-Dug-Wells-OXFAM.pdf [Oxfam is an international confederation of 21 independent non-governmental organizations (NGOs), focusing on the alleviation of global poverty, founded in 1942] - Wikipedia
  
  Abstract:
  

  Hand dug wells may need repairing, cleaning and disinfecting after inundation by flood water, inundation of seawater as in the case of a tsunami, materials entering as the result of mudslides or as a result of hurricanes, or simply after long periods of limited maintenance or neglect.
  
  If work has been undertaken on the well to try to increase its yield through, widening or lining the well, then cleaning and / or disinfection will also be appropriate.

  This Technical Brief identifies the process for repairing, cleaning and disinfecting hand dug wells and also discusses the OXFAM kits which can be used for these processes.

• USDA, OPERATION ANDMAINTENANCE MANUAL FOR HAND PUMPS [PDF] (1999) USDA, United States Department of Agriculture, Forest ServiceTechnology & Development Program 2300 Recreation Management November 1999 9923 1209—SDTDC retrieved 2020/04/23, original source: https://www.fs.fed.us/t-d/pubs/pdf/99231209.pdf
  
  Excerpts: Sanitary surveys on hand pumps in Region One identified some recurring problems at many of the installations. Some of these deficiencies were associated with the design of the hand pump stands, and some were associated with pump installations, such as, drainage, slabs, etc.
  
  The Region’s standard drawing for the installation of hand pumps was approved in 1978 based on the data gathered from those sanitary surveys.
  
  The treatment system should not be used to cover up obvious sanitary deficiencies in the well hand pump installation.
• U.S. CDC, GUIDELINES for TREATING WELL WATER (2024) (U.S. CDC Website) US Centers for Disease Control, local backup copy saved as Well-Water-Treatment-CDC.pdf
• U.S. CDC, HOW TO DISINFECT WELLS AFTER AN EMERGENCY (2025) (U.S. CDC Website) U.S. Centers for Disease Control, local backup copy saved as Well-Disinfiection-After-Emergency-CDC.pdf
• U.S. CDC, DISINFECTING WELLS FOLLOWING AN EMERGENCY [PDF] (Wells County Indiana, USA website), U.S. Centers for Disease Control, local backup copy saved as Emergency-Well-Disinfection-CDC.pdf
• US EPA, POTENTIAL WELL WATER CONTAMINANTS AND THEIR IMPACTS [PDF] U.S. Environmental Protection Agency, retrieved 2020/04/23 original source: https://www.epa.gov/privatewells/potential-well-water-contaminants-and-their-impacts
• US EPA, WHAT TO DO WITH YOUR PRIVATE WELL AFTER A FLOOD [PDF] (at CDC Website) A guide to well and pump inspection and emergency disinfection of wells that have been flooded (with illustrated instructions), also En Espanol.
• Ifabiyi, I.P., Depth of Hand Dug Wells and Water Chemistry: Example from Ibadan Northeast Local Government Area (L.G.A.), Oyo-State, Nigeria [PDF] (2008) I. P. Ifabiyi, Department of Geography, Faculty of Business and Social Sciences, P.M.B 1515, Ilorin, Nigeria E-mail: tokunifabiyi @yahoo.com, J. Soc. Sci., 17(3): 261-266 (2008), Web search 4/13/12, retrieved 2-026/08/09, local backup copy saved as Dug-Well-Depth-Chemistry-Ifabiyi.pdf
  Quoting:
  
  ABSTRACT The paper attempts an examination of the relationships between water chemistry and depth of hand dug wells in a densely populated (16,679-people/km2) part of Ibadan, Nigeria. Multivariate procedures of multiple and stepwise regression analyses were adopted.
  
  Results of the multiple regression and correlation showed that Coliform count., pH , total hardness (TH), calcium (Ca+),magnesium (Mg+ ), iron (Fe+) and chloride (Cl- )increase with increasing depth while nitrate (NO3 - )and bicarbonate (CO3 -)2 reduce with depth.
  
  All the examined parameters were significant at 0.05.
  
  Further, the result of R2 showed that the relationship explains 68.88% of the variance; while, the stepwise regression suggest chloride to be the most important chemical parameter (R2 of 38.11%).
  
  That is related to well’s depth. The paper calls for further research.
  
  Excerpt from conclusions:
  
  The relationships between depth and chemical parameters are discussed. For example, some parameters have positive relationship with one another, while others are negative. The result indicates that significant relationship exists between depth and all the examined parameters.