How Much Water Do Pet Rats Need – Daily Drinking Guide

We all know that water is vital for life, so of course, it’s going to be important for your rat’s health.

But rats are so much smaller than we are that it can be hard to know how much water they should be drinking.

In this article I’ll give a guide to how much water a healthy rat should be drinking every day. I’ll also look at reasons why they might not be drinking and easy ways you can check they are.

Adult rats will usually each drink around 1 – 2 oz of water per day (30 – 60 ml). The amount they drink can depend on various external factors such as temperature and diet. You should monitor your rat’s water intake as drinking low amounts and excessive amounts can both be signs of underlying health conditions.

How much water do pet rats drink

You can expect an adult rat to drink between 1 – 2 oz of water every day, that’s equivalent to 30 – 60 ml.

That’s for an individual rat, so multiply it against the number of rats you have to get the total expected daily requirement.

You should try to have at least double that amount in your rat’s water bottle most of the time as external factors can influence how thirsty they are, you don’t want them to run out of water on a particularly hot night for example.

My pet rat is drinking lots of water

There are good reasons why rats might be drinking more water than usual that shouldn’t raise any concern.

Just like humans, there are certain conditions where your pet rat will become particularly thirsty. Let’s look at these first and then discuss some reasons which may be more concerning.


Your rats will need more water during hot days, if you’re due for a hot summer then your fancy rat may very well exceed the daily water guidelines.

If the excess drinking is just a reaction to a hot day then there’s no need for concern.


The amount of activity your rat has will have a similar effect on them as high temperatures. 

They will need more water in order to cool down.

This means they need more water than usual to re-hydrate. So if you have had your rat out of its cage for long periods playing with it, it may just have developed a bit of extra thirst


What your rats eat will also have an effect on how much they need to drink. Dry meals such as standard rat food won’t contain much moisture.

That doesn’t mean there’s anything wrong with feeding your rats dry food, just make sure they have plenty of water to go with it.

There are plenty of high-water-content treats you can give your rats occasionally such as bell peppers. That’s perfect for hot days where the extra moisture might be just what they need.

Health issues

Certain health issues can cause an increased thirst for rats.

This can often be helpful to the rat’s health, if for example, they were suffering from diarrhea then you would expect them to drink more in order to rebalance their fluid levels.

However, these short term conditions should fade after a few days.

If your rat continues to drink excessive amounts of water and it isn’t obviously connected with one of the situations shown above then it could be a sign of more serious health issues.

Excessive water intake can be a sign of bladder infection or other health issues.

If you notice your rat has been drinking excessive water over a prolonged period for no obvious reason then you should consult with your vet.

How do I know if my rat is drinking water

The best way to monitor how much water your rat is drinking is to use a water bottle with the volume already marked on.

This water bottle on Amazon is ideal. It’s inexpensive and comes in a variety of sizes. If you just have a couple of rats I’d choose the medium-sized one, you can view it on Amazon here.

If you already have a water bottle you like, but it doesn’t have measurements on then you can just fill a measuring jug to 2 oz first, and then pour the water into your water bottle.

Mark the level of the water with a permanent marker and there you have it, a homemade measurement water bottle.

Either way, you’ll now be able to monitor how much water your rat is drinking every day.

My pet rat is not drinking water

If a rat stops drinking any water at all it can be a large indicator that something is wrong with their health.

Whilst rats can often be put off their food by stress or illness, they will rarely stop drinking for extended periods as dehydration can set in very quickly.

Whilst a rat can go for quite a long time, maybe a week or so, without eating and have no health effects, a few days without drinking water could be life-threatening, so it’s important that you monitor them closely if you suspect they have stopped drinking.

Try encouraging your rat to drink by placing a bowl of water in their cage rather than just the bottle.

Rats don’t usually go more than a day without having some water if you think your rat has gone a whole day without drinking and still doesn’t seem to be interested in any water you put in front of them you should consider taking them to a vet.

In the meantime, you can feed the moisture-rich foods like peppers to keep them hydrated.

My rat’s water bottle doesn’t work

Sometimes rat owners report that their water bottle doesn’t seem to be dispensing water.

The first thing to check is whether it’s working properly. Use your finger to push the drinking end, the water should come out.

If not, or there is significant resistance when you try to push it then you may need a new bottle. This one on Amazon is ideal.

If it is working there may be another issue. Some rats may not realize that the bottle dispenses water at first, try pushing the end with your finger to moisten it and get a little droplet to gather.  

That should hint to your rat that the bottle equals water.

If they still aren’t drinking then place a small bowl of water in their cage and see if they are happy to drink from that.

Although rare, some rats do actually prefer to drink from a bowl rather than a water bottle.

If they still won’t drink then they might have a health condition and you should consult with your vet.

Rat water bottle recommendation

The ideal water bottle for rats is a large one with volume measurements on it.

This one on Amazon is perfect and inexpensive.

It comes in three sizes, I’d recommend either the medium or large, depending on how many rats you have.

Hamster water bottles tend to be too small for rats as they drink much more water.

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