The most delicate issue of a mikveh is how thick is the concrete? If it is thick enough that it could be lifted whole and stay in one piece, then it is a vessel--and not good as a Mikveh.
Another major issue with the Mikveh is that it needs to be a natural body of water.
אך מעיין ובור מקוה מים יהיה טהור מה מעין בידי שמים אף מקוה בידי שמים
So it is hard to make it by man's hands and still have it be natural. The issue really is from a Gemara that says if a pipe is formed and then attached that makes the mikveh no good. But if it is attached and then hollowed out that is OK. To the Rashbam that is a pipe of stone or wood.
But later the Gemara says that is only according to the idea that drawn water is no good only from the words of the sages. But if drawn water is no good from the Torah then even attached and then hollowed is no good. And that applies to either rain water or even drawing off from a spring.
So the issues just keep getting more and more.
[Unless we would go with R. Isaac who in fact holds a mikve made of drawn water is no good only to the sages and that would leave the teaching of the Gemara in its place-snce the Gemara itself says it is going according to that opinion. A further point is that Tosphot says the case is if the pipes were made to receive and hold something in them--not just to have something passing through them. According to that, the plastic pipes or wood would be fine since even when made and later attached they do not receive uncleanliness.]
Further reason to say one needs a river is the Rambam that brings the statement of the Gemara of a pipe plainly -not like Tosphot that says it has to be מקבל טומאה. But one reason to be lenient is that R. Hananel and the Rashbam hold the law is like R. Eliezer that what is attached to the ground is like the ground.
[I should mention that I would feel a lot better about this if I would have either spent more time on Tosphot or have learned it with my learning partner. Here I am just giving the basic outline of the subject but there is plenty of work that I still need to do on Tosphot.]
All I am saying is if you have a spring or river or ocean, anywhere around, that is the best idea.
I know girls have trouble in this area because most rivers are pretty cold. I hope that girls start to develop a rougher bark and get less delicate.
In NY a woman could go to the ocean on the seventh day and be OK at night. In Israel there are often springs and rivers around. [A sea or ocean are not springs, so do not work for a zava. But are okay for a nida. ]
[Since my general approach is that once there is a Rishon that allows something, then one can depend on that, then one could just go with R. Isaac and the first Tosphot in which case things are OK. The only thing is it is clearly better to go to an authentic natural body of water because of R. Tam.]
I want to make it clear that even in cold winter it is possible to go a cold river much more easily that people realize. The reason is if you put your foot into cold water and then take it out, the body automatically starts to drawn the blood from the outer areas. So when you put your foot in a second time it does not feel cold at all. And the same goes with one's legs. So to dip in a river is possible if one does so gradually in small steps. That is to put the feet in an then take them out. Then the legs. Then the whole body. Also going in with clothing that is not tight also makes it much easier.
Another major issue with the Mikveh is that it needs to be a natural body of water.
אך מעיין ובור מקוה מים יהיה טהור מה מעין בידי שמים אף מקוה בידי שמים
So it is hard to make it by man's hands and still have it be natural. The issue really is from a Gemara that says if a pipe is formed and then attached that makes the mikveh no good. But if it is attached and then hollowed out that is OK. To the Rashbam that is a pipe of stone or wood.
But later the Gemara says that is only according to the idea that drawn water is no good only from the words of the sages. But if drawn water is no good from the Torah then even attached and then hollowed is no good. And that applies to either rain water or even drawing off from a spring.
So the issues just keep getting more and more.
[Unless we would go with R. Isaac who in fact holds a mikve made of drawn water is no good only to the sages and that would leave the teaching of the Gemara in its place-snce the Gemara itself says it is going according to that opinion. A further point is that Tosphot says the case is if the pipes were made to receive and hold something in them--not just to have something passing through them. According to that, the plastic pipes or wood would be fine since even when made and later attached they do not receive uncleanliness.]
Further reason to say one needs a river is the Rambam that brings the statement of the Gemara of a pipe plainly -not like Tosphot that says it has to be מקבל טומאה. But one reason to be lenient is that R. Hananel and the Rashbam hold the law is like R. Eliezer that what is attached to the ground is like the ground.
[I should mention that I would feel a lot better about this if I would have either spent more time on Tosphot or have learned it with my learning partner. Here I am just giving the basic outline of the subject but there is plenty of work that I still need to do on Tosphot.]
All I am saying is if you have a spring or river or ocean, anywhere around, that is the best idea.
I know girls have trouble in this area because most rivers are pretty cold. I hope that girls start to develop a rougher bark and get less delicate.
In NY a woman could go to the ocean on the seventh day and be OK at night. In Israel there are often springs and rivers around. [A sea or ocean are not springs, so do not work for a zava. But are okay for a nida. ]
[Since my general approach is that once there is a Rishon that allows something, then one can depend on that, then one could just go with R. Isaac and the first Tosphot in which case things are OK. The only thing is it is clearly better to go to an authentic natural body of water because of R. Tam.]
I want to make it clear that even in cold winter it is possible to go a cold river much more easily that people realize. The reason is if you put your foot into cold water and then take it out, the body automatically starts to drawn the blood from the outer areas. So when you put your foot in a second time it does not feel cold at all. And the same goes with one's legs. So to dip in a river is possible if one does so gradually in small steps. That is to put the feet in an then take them out. Then the legs. Then the whole body. Also going in with clothing that is not tight also makes it much easier.
