When and How to Give Water to Babies Safely

Water plays a vital role in a baby’s health, but when, how, and how much water to offer infants is often misunderstood. While breastmilk or infant formula provides most of a baby’s fluid needs in early life, questions commonly arise about water safety, preparation of formula, and whether additional water is needed.

This article explains how different water sources vary in safety, when water may or may not be appropriate for babies, and how to reduce potential risks associated with contamination, mineral content, and overconsumption.

Non-bottled water

The 3 most common supplies of non-bottled water are...  

• Municipal water supplies
• Private wells or bore water
• Rainwater tanks

1. Municipal water supplies

Like any water supply (including that used by bottled-water manufacturers), municipal water supplies are vulnerable to contamination from the environment. To reduce the level of contaminants and improve its quality, the water is pumped through a series of filters and disinfected at water treatment plants.

There are concerns that the water treatment process may create potential health problems. Municipal water is commonly treated with chlorine to eliminate harmful micro-organisms. Chlorine can react with naturally occurring organic matter to produce by-products called trihalomethanes. Also, some municipal water supplies add fluoride to the water. Fluoridated water is viewed as a health benefit by many and a health hazard by others.

Water quality varies from one water supplier to another, even within the same country. While tap water from some suppliers is considered of good or even excellent quality, other suppliers provide water that is considered of poor quality.

Lead can get into your water supply after it has left the treatment plant. (Lead is a toxic metal that can pose a long-term health risk for infants and small children.) Lead may be a concern in older homes with older plumbing.

How to be sure your water is safe?

Municipal water is tested regularly to ensure it meets health standards.

To check the water quality in your area, ask your water supplier for a copy of their annual water quality report. If lead may be a problem (for example, in older plumbing), ask about testing and consider having your tap water tested so you can determine what your household plumbing might be contributing to your water supply.

2. Private well or bore water

Water from some private wells is NOT safe for infants and pregnant women.

Shallow well water may contain by-products of farm fertilisers; particularly nitrates, and may also contain contaminants such as lead or arsenic. High levels of nitrates in drinking water can reduce the ability of a baby's blood to carry oxygen, resulting in a serious condition called methaemoglobinaemia.

If you are on a spring or well supply with no disinfection, there is increased vulnerability to bacterial contamination.

How to be sure your well water is safe?

Your local health department can tell you which contaminants are typically found in your area. It can also supply a list of certified labs to test the water for you. Be aware that any water system can be temporarily affected by spills and agricultural runoff, including pesticides and insecticides.

3. Rainwater tanks

Anything that happens to fall on your roof or collect in your gutter can also collect in your rainwater tank. Bacterial and viral contamination in tank water can occur and elimination cannot be guaranteed, even with chlorination or other methods of disinfection.

How to be sure your rainwater is safe?

Bacteriological tests are available to determine if water is safe for human consumption. Contact your local health department for information on how and where these tests are performed. Regular testing is recommended if rainwater is used for drinking or formula preparation.

Why is water important for babies?

Water is the most abundant substance in the human body. Every cell in our body contains water. Body water of infants and children contributes to around 65% - 75% of their total body weight; for adults the figure is around 60%.

Water is necessary for all biochemical processes that occur in our body. Our body uses water for digestion, absorption, circulation, transporting nutrients, building tissues, carrying away waste and maintaining body temperature.

Our survival is dependent on water. We can survive many weeks without food but only a few days without water. A lack of body water results in dehydration, a serious life-threatening condition.

Home filtration systems

Home water filtration systems are also increasing in popularity. The different types of filtration systems vary significantly in their effectiveness in removing different contaminants (for example, heavy metals, bacteria, parasites) in water. Correspondingly, they can also vary significantly in cost.

Before purchasing expensive filtration systems, have your tap water analysed. Water analysis is usually inexpensive and will help to identify any potential problems. Test results will help you determine if your water needs to be treated and, if so, the best option to use.

The 3 most popular filtration devices are...

• Carbon filters
• Reverse osmosis filters
• Distillers

1. Carbon filters

When water flows through carbon filters, contaminants adsorb (stick) to the surface of the carbon filter.

ADVANTAGES

• Carbon filters treat general taste and odour problems, including chlorine residue.
• Carbon filters can reduce some organic chemicals (for example, certain pesticide residues).
• Carbon filters are often the least expensive of the 3 main treatment methods listed here.

DISADVANTAGES

• Carbon filters are generally not effective at removing many dissolved minerals and some contaminants (for example, nitrates) and are not designed to reliably remove all micro-organisms.
• The effectiveness of carbon filters declines over time. Filters need to be cleaned or changed regularly. If the filter becomes clogged or wears out before it is replaced, it can become a breeding ground for bacterial growth.

For infant formula: If you use filtered water, maintain the filter according to the manufacturer’s instructions. When preparing powdered infant formula, use freshly boiled water as described above.

2. Reverse osmosis filters

A reverse osmosis filter works by passing water, under pressure, through a special semipermeable membrane that can reduce a wide range of dissolved substances and many contaminants. These systems are more powerful than simple carbon filters and are also more expensive.

ADVANTAGES

• Reverse osmosis can reduce dissolved salts and some contaminants such as nitrate, fluoride, and some metals.
• Some systems do not use electricity, and the cost per litre of treated water can be less than distillation.

DISADVANTAGES

• Reverse osmosis systems can waste a lot of water.
• They can be slow and may be expensive to install and maintain.
• Efficiency drops with lower water pressure.
• The membrane should be changed periodically to maintain effectiveness.
• Reverse osmosis can reduce minerals naturally present in water.

For infant formula: Reverse osmosis water can be used if it meets drinking-water standards. When preparing powdered infant formula, use freshly boiled water as described above.

3. Distillers

Water distillers work by boiling water and then condensing the steam into purified water. Some units then run the water through a carbon filter. Distillation can remove many contaminants, including micro-organisms and some chemicals.

ADVANTAGES

• Distillation (especially when combined with carbon filtration) can be an effective means of home water treatment.

DISADVANTAGES

• They can be expensive to purchase and to run because they use a lot of electricity.
• Distillers require regular cleaning, can be noisy, and may give off heat.
• Distillation removes minerals naturally present in water.

For infant formula: Distilled water can be used if it meets drinking-water standards. When preparing powdered infant formula, use freshly boiled water as described above.

Bottled water

Bottled water is widely available in many types and brands.

Some people drink bottled water because they prefer the taste to tap water. Others drink it because they believe it is safer than tap water, however safety depends on the source, handling, and storage conditions.

How can you tell if bottled water is safe?

No bottled water should be presumed to be sterile.

Even where bottled water is of high quality, improper or prolonged storage conditions can increase bacterial content once it leaves the manufacturer.

• Mineral water may contain higher levels of minerals and is generally not recommended for routine use in infant formula preparation.
• Spring water can contain varying mineral levels and is not recommended for routine use for infant formula, except in an emergency.
• Sparkling or carbonated water is not recommended for infants.

In an emergency: You may use bottled drinking water to prepare formula, but use freshly boiled water as described above.

Water softeners / water conditioners

Artificially softened water is not suitable as drinking water for infants.

Water softeners have little to do with filtration/purification. A water softener does not remove microbiological contaminants that cause illness. They simply make the water more pleasant to wash with.

Water softeners soften or condition hard water by replacing hard ions in the water (like magnesium and calcium) with sodium or potassium ions. Water containing high levels of sodium or potassium should not be used for drinking, making coffee, juice, infant formula, or cooking.

Can water be harmful to a baby?

Offering occasional, small amounts of safe drinking water will not harm a healthy, thriving breastfed or formula-fed baby, even if offered prior to starting solids.

However, in unusual circumstances it is possible to upset a baby's electrolyte balance by providing large amounts of water. In extreme cases, water intoxication can occur if a child takes in large amounts of fluid without corresponding electrolytes (for example, giving over-diluted formula, or giving large amounts of water).

Provided water is not offered in place of milk (breastmilk or infant formula) and a healthy child is not forced to drink more water than he wants, water intoxication is unlikely to occur.

Is it necessary to give water to babies?

Water is important to babies, as it is to everyone. However, babies receive most of their water needs from breastmilk or infant formula and there is little need for additional water before a child starts eating solid foods.

Before starting solids

In cool or moderate climates it is generally not necessary to give additional water to young babies. Breastmilk contains approximately 87–90% water and infant formula contains approximately 85% water (provided it is prepared correctly).

In warm or dry climates, additional water may be considered for some formula-fed babies, provided it does not replace formula feeds. Breastfed babies generally do not need additional water but may need more frequent breastfeeds.

After starting solids

Most foods contain water, even when it may not be obvious. Fruits and vegetables contain around 75% - 95% water; fish, red and white meat 50% - 70% water. Even “dry foods” such as grains and cereals contain some water.

With a lower water content, solid food increases the renal solute load (workload on a baby’s kidneys). Once a child starts eating solid food, small amounts of additional water should be offered regularly.

Other frequently asked questions

1. Is it true breastfed babies don't need extra water?

Prior to starting solids (at around 6 months of age) a thriving exclusively breastfed baby generally does not need additional water for hydration. After commencing solids, additional water is recommended.

2. What are the reasons to give extra water to a formula fed baby?

• Satisfy thirst.
• Relieve symptoms of constipation.
• Satisfy a sucking urge not related to hunger. (See Hungry baby for reasons why babies can appear hungry.)
• Delay feeds (overfeeding young babies can cause gastrointestinal symptoms related to lactose overload).
• Establish healthy dietary habits (acceptance of water).

3. How much water should I give my baby?

This depends on your child’s state of health, age, weight, level of activity, climate and whether or not he’s started eating solid foods.

As a general guide for healthy babies and children:

• Under 6 months: Do not give water unless instructed by your healthcare provider.
• 6 - 12 months: Offer small amounts of water with meals and as needed in hot weather, without replacing milk feeds.
• Over 12 months: Allow your child to have water as he chooses. Make sure it is readily available.

4. When is the best time to offer a baby water?

Do not give water close to feeding time (for example, if a milk feed is due within an hour), as your child’s tummy may still be full from the water when the next feed is offered and he may not drink as much milk as he would otherwise.

5. How can I tell if my child is getting enough water?

If your child is healthy and thriving (gaining enough weight for his age) and has regular wet nappies each day.

6. Do I need to boil the water before giving it to my baby?

Regardless of the source or type of water used, it is not sterile. This means it contains varying amounts of micro-organisms such as bacteria, protozoa and parasites.

For powdered infant formula: Use freshly boiled water that has been cooled for no more than 30 minutes (so it remains at least 70°C) before adding formula powder.

For drinking water: Recommendations vary by location and age. Many health providers recommend boiled (then cooled) water for younger infants, particularly where water quality is uncertain. Because water quality varies from place to place, check with your local healthcare provider for advice in your area.

If boiling water, boil for 1 minute. Longer boiling can concentrate minerals as water evaporates.

7. Isn't there a lot of water in fruit juice and milk?

Fruit juice contains high levels of sugars (see fruit juice). Water is the best drink for babies apart from milk.

Written by Rowena Bennett

About Rowena

Rowena Bennett (RN, RM, CHN, MHN, IBCLC) is a leading infant-feeding and sleep specialist and author of several books on infant feeding and behaviour, including the widely acclaimed “Your Baby’s Bottle-Feeding Aversion: Reasons & Solutions". With over three decades of clinical experience across child health, midwifery, mental health, and lactation, she has helped thousands of families worldwide understand and resolve complex feeding challenges through her evidence-based, baby-led approaches.