Groundwater

Overview

Groundwater is water that sits underground, stored in tiny spaces and cracks in soil, sand and rock. It is the source for most wells and springs, and in many places it is also the water that feeds rivers and lakes. For millions of people, groundwater is simply the water that comes out of the tap. Because it is out of sight, it is easy to forget that it can pick up germs, chemicals or naturally occurring metals as it moves through the ground. When that happens, drinking the water can affect your health — most often by causing stomach bugs, and sometimes through long-term exposure to substances that are harmful over many years.

Groundwater itself is everywhere — it is the world's largest store of fresh water that is easy to use. Problems with groundwater quality are also common in many regions, especially where wells are old, shallow, or close to farms, septic tanks or industry. Not every well has a problem, and many are perfectly safe. Regular testing is what tells you where you stand.

Anyone who drinks well water, spring water or water from a small local supply is affected. This includes people living in rural or farming areas, households with private wells, campsites and small communities. Babies, young children, pregnant women, older adults and people with weakened immune systems are more likely to become seriously unwell if water is contaminated. People on public water supplies are also protected by groundwater, because many towns draw at least part of their water from underground sources that are monitored and treated.

Symptoms

Common symptoms

• Diarrhoea (loose or watery stools)
• Feeling sick or being sick (nausea or vomiting)
• Stomach cramps or pain
• Mild fever
• Headache and feeling generally unwell
• No symptoms at all — many contaminants cause no obvious signs in the short term

Symptoms in children

• More frequent watery stools and quicker dehydration
• Fewer wet nappies or less urine than usual
• Dry mouth, sunken eyes or no tears when crying
• Being unusually sleepy, irritable or floppy
• Refusing feeds or drinks
• Vomiting that stops them keeping fluids down

Symptoms in older adults

• Dehydration that can develop quickly and cause confusion
• Dizziness or falls when standing up
• Feeling very tired or weak
• Loss of appetite
• Diarrhoea that lasts longer than in younger adults

Causes

Main causes

• Germs (bacteria, viruses and parasites) getting into groundwater from septic tanks, animal waste, or flooded wells
• Fertilisers, pesticides and manure from farming seeping into the ground
• Chemicals from industry, fuel tanks, dry cleaners or old landfill sites leaking into the water table
• Naturally occurring substances in the rock, such as arsenic, fluoride, manganese or radon
• Salt water creeping into coastal wells when too much water is pumped out
• Poorly built, cracked or uncovered wells and boreholes that let surface water and dirt in
• Flooding, which can wash contamination into a well head

Risk factors

• Having a private well, spring or small unmonitored supply
• A shallow well, or one that is old and in poor repair
• Living near farmland, a landfill, a factory or a fuel station
• Recent heavy rain or flooding near your well
• Never having had your water tested, or not testing it for many years
• Having a baby, young child, or someone with a weakened immune system at home
• Living in an area known to have naturally high levels of arsenic or other metals

When to see a doctor

See a doctor urgently if:

• Diarrhoea or vomiting that will not stop, or signs of dehydration
• Blood in the stool or vomit
• A high fever, especially with severe stomach pain
• A young child, pregnant woman or older adult who becomes unwell after drinking suspect water
• Any symptom you think may be linked to your water supply

Book a routine appointment if:

• You want advice on how to test your well water
• Your test results show a contaminant and you are not sure what it means
• You have had repeated bouts of stomach upset and cannot work out why
• You are planning a pregnancy or have a newborn at home and use well water
• You are thinking about installing a water treatment system

Diagnosis

A doctor will usually start by asking about your symptoms, how long they have lasted, and whether others in your household are affected. They will ask where your drinking water comes from and whether it has ever been tested. Most short bouts of diarrhoea and vomiting are diagnosed from the story alone. If symptoms are severe, lasting, or keep coming back, stool tests can look for specific germs. Separately, your water itself can be tested — this is done by a laboratory through your local water or environmental health service, not by your doctor, but the results are very useful to share with your doctor.

Tests that may be done

• Stool sample to check for bacteria, viruses or parasites
• Blood tests if you are very unwell or dehydrated, or if long-term exposure to a chemical is suspected
• A urine test if dehydration or a kidney problem is a concern
• Water testing by a laboratory for germs (such as coliform bacteria), nitrates, arsenic, fluoride and other metals
• A repeat water test after heavy rain, flooding, or repairs to your well

What to expect at your appointment

Most appointments are quick and involve questions rather than tests. If a stool sample is needed, you will be given a pot and instructions, and results usually come back within a few days. Water testing is arranged separately and typically takes one to two weeks. Your doctor can help you understand the results and decide whether anything needs to change at home.

Treatment

Treatment depends on what is causing the problem. If a germ in the water has made you ill, the main job is to replace the fluids and salts you have lost, and most people recover within a few days. If a chemical or metal in your water is the issue, the treatment is usually to stop drinking that water and to fix or treat the supply — the body then clears many substances over time, and your doctor will monitor you if needed. In every case, the most important step is to make sure the water you drink is safe.

Self-care at home

• Drink plenty of fluids — small, frequent sips are easier than large amounts at once
• A pharmacy oral rehydration drink can replace salts lost through diarrhoea; ask your pharmacist which one suits you
• Keep eating simple foods as you feel able; there is no need to starve
• Wash hands well with soap after the toilet and before preparing food, to avoid passing illness to others
• Stop using the suspect water for drinking, cooking, brushing teeth and making ice until it is tested or treated
• Use bottled water or boil water and let it cool if your local service issues a boil-water notice

Medical treatments

Doctors treat waterborne illness by supporting you through it — mainly by replacing fluids and salts, by mouth where possible and through a drip if you are very dehydrated. Specific medicines are only needed for certain causes, and your doctor will decide whether any are appropriate for you. If a chemical such as arsenic or a high level of nitrate has been found in your water, your doctor may arrange repeat tests over time to check your levels and will focus on removing the source. They may also refer you to a specialist or to a public health team. Never start, stop or change any medicine without talking to your doctor or pharmacist first.

When is surgery considered?

Surgery is not used to treat illness caused by contaminated groundwater. It is only relevant in rare cases of severe complications, which your medical team would discuss with you if they ever arose.

Living with this condition

Living safely with a private water supply mostly means a few simple habits: know where your water comes from, test it regularly, and keep the well head clean and covered. Keep a small stock of bottled water at home in case of flooding or a boil-water notice. If a contaminant has been found, use an alternative safe source while the problem is fixed, and tell anyone who shares your supply, such as neighbours or a landlord.

Lifestyle tips

• Test your well at least once a year, and again after flooding, repairs or any change in taste, smell or colour
• Keep the area around the well head clear of animals, chemicals, compost and fuel
• Make sure the well casing is sealed and slopes so that surface water runs away from it
• Have your septic tank checked and emptied on the recommended schedule
• Store and handle garden and farm chemicals well away from the well
• If you use a filter or treatment system, change the cartridges as instructed

Diet and exercise

There is no special diet for water-related illness — the priority is staying well hydrated. During and after a bout of diarrhoea, sip fluids often, and eat light, familiar foods as your appetite returns. Once you have recovered, normal eating and everyday activity are fine. If you have a long-term condition affected by what you drink, such as kidney or heart problems, ask your doctor for advice tailored to you.

Mental health and emotional wellbeing

Being worried about something as basic as the water in your home can be stressful, especially if you have young children or if the problem has dragged on. It is completely understandable to feel anxious. Talking it through with your doctor, a public health service or a neighbour in the same situation often helps, and putting a clear plan in place — test, treat, retest — usually eases the worry. If anxiety is affecting your sleep, mood or daily life, please tell your doctor. If you ever feel unable to cope, contact your local mental health crisis line or emergency services.

Prevention

Much of the harm from groundwater can be prevented. Regular testing, a well-built and well-maintained well, careful handling of chemicals, and prompt action after flooding greatly reduce the risk. If you are on a public supply, water is treated and monitored for you, so the main thing is to follow any boil-water notices promptly.

Vaccines

There is no vaccine against groundwater contamination itself. Some waterborne infections do have vaccines — for example, routine childhood vaccines protect against some causes of severe diarrhoea. Ask your doctor or pharmacist whether your vaccinations, and your children's, are up to date.

Screening programmes

There is no medical screening test for groundwater exposure. The equivalent is water testing: test a private well at least once a year for germs and nitrates, and ask your local service whether arsenic, fluoride or other local contaminants should be checked. Test again after flooding, after repairs, or if you notice any change in taste, smell or colour.

Complications

If left untreated

• Dehydration, which can become serious quickly in babies and older adults
• Prolonged or repeated diarrhoea, with weight loss and tiredness
• Rarely, more serious infections spreading beyond the gut
• Over many years, ongoing exposure to arsenic can raise the risk of skin problems and some cancers
• Long-term exposure to high nitrate can reduce the blood's ability to carry oxygen, especially in babies (a condition called blue baby syndrome)
• Too much fluoride over years can cause mottled teeth and, at very high levels, bone problems

Long-term outlook

The outlook is generally very good. Short bouts of waterborne illness usually settle within a few days, and once a contaminated supply is fixed or treated, most health effects improve. Long-term problems are largely avoidable with regular testing and simple well maintenance. If a contaminant has been found in your water, taking action early gives the best chance of staying well — and your doctor and local water service can guide you through each step.

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