Why monks filter water? What about microorganisms?

Can a monk filter out microorganisms by a cloth?
What is the position of Vinaya regarding this?

The cloth is called a water-strainer

It can be found in the KD 15

Now at that time on a certain road there was water that was not allowable (for) there was no strainer. They told this matter to the Lord. He said: “I allow, monks, a strainer.” A little piece of cloth was not enough. “I allow, monks, a strainer on a ladle.” The little piece of cloth was not enough. They told this matter to the Lord. He said: “I allow a regulation waterpot.”

For water that was not allowable is defined in: Bu-Pc 62 and Bu-Pc 20

It can be considered that micro-organisms is equivalent to “living things” in this context.

So, why is filtered water allowed and non-filtered water not allowed, while both contains microorganisms?

Ah I am also curious if at that time they have any knowledge about such things as micro-organisms (if you define micro-organisms as bacteria or virus, etc. that can’t be seen with naked eyes).

Otherwise, it’s quite fair to say that they are trying their best to remove “living things” in the water before consumption. It’s also a reasonable rule that can be followed.


Not defined as “sentient.”

1 Like

What are the kinds that are sentient?

Micro-organisms were unknown until the invention of microscopes AFAIK, which was in the 1600s AD. People thought diseases were caused by imbalances of the elements, miasma, possession by spirits, etc. in ancient times because they didn’t know about the micro-organisms that cause illnesses.

1 Like

Coincidentally, there is a lively discussion going on about that very question right now :slight_smile:

As modern people who know about microorganisms, what actions should we take additionally?

In case we already know or doubt that a group of microorganisms are sentient, what should we do about them?

Anyone here got an image that monks start to have to carry a microscope with them as among the requisites? :crazy_face:

1 Like

Can we ignore other very tiny beings in the same way we do to microorganisms? Is there a minimum body size?

Well, I guess that such a criteria as “living being that can be seen by naked eyes” is a reasonable rule to follow for monks, no? Or maybe something as a guide as lines on the palm?

Otherwise, you will have to wait for comments from experts in Vinaya as Bhikkhu @Brahmali

I have also heard about this criteria used by some people. Is it backed by texts (at least implicitly)?

It’s in the Chinese Vinaya Bu-Pc 52. I am not sure if there is an equivalent in Pali version or in Pali commentary.


Here too: Is there such mention in the Sutta about Microbes being predicted by the Buddha? - Discussion - Discuss & Discover (suttacentral.net)

Boil water or filter until no more microbes, for the sake of health. It’s basically wisdom passed down from the time of diseases spread via unclean water.

It is distressing to find visible living beings (mosquito larvea) in your water supply. I had this problem for 3 months at my kuti. They would come rushing out the tap in quite a shock that they had been brought into daylight. It turned washing my alms bowl into a 40 minute endeavour while I filtered and rinsed and peered.

There are two rules related to water and little critters.
Bhikkhu Pacittiya 20 and Bhikkhu Pacittiya 62 The Bhikkhuni’s have the same rules with different numbers.


If this is really all out of concern of the welfare of living beings, what happens with the filter and living being in it? Are there rules regarding how one has to treat the filter?

No there are not. (Someone please correct me if there are.) Those days it would have been a simple cloth filter. Remember this is for filtering visible organisms. I would assume that it was understood that you would simply rinse the cloth when you were done simply as a matter of keeping things clean.


Does that mean one does not really protect the lifes of the visible organism? They still die while rinsing the cloth?

“If anyone were to say that just as a person does a deed, so is his experience is determined by it, and if this were true, then living the holy life would not be possible, there would be no opportunity for the overcoming of suffering. But if anyone were to say that a person does a deed that is to be experienced, so does he experience it, then living the holy life would be possible, there would be an opportunity for the ending of suffering. For instance, a small evil deed done by one person may be experienced here in this life or perhaps not at all. Now, what sort of person commits a small evil that takes him to hell? Take a person who is careless in the development of body, speech and mind. He has not developed wisdom, he is insignificant, he has not developed himself, his life is restricted, and he is miserable. Even a small evil deed may bring such a person to hell. Now, take the person who is careful in development of body, speech and mind, He has developed wisdom, he is not insignificant, he has developed himself, his life is unrestricted and he is immeasurable. For such a person, a small evil deed may be experienced here or perhaps not at all. Suppose someone throws a grain of salt into a little cup of water. That water would be undrinkable. And why? Because the amount of water is small. Now, suppose throws a grain salt in River Ganges. That water would not be undrinkable. And why? Because the amount of water is great”