How far does one have to travel to get water to wash for tefilah?

There is an obligation to wash in preparation for davening Shacharis, Mincha and Ma’ariv. One who washed for Mincha and intends to daven Ma’ariv immediately afterwards does not need to wash again. B’dieved, if a person failed to wash, his tefilah is still valid. If a person’s hands are dirty while he is in transit and there is no water available, he must travel forward for up to seventy-two minutes to a place where water can be found. Alternatively, if he knows that there is water behind him or if he is not traveling, he must travel up to eighteen minutes. One should not miss either tefilah b’tzibur or zman tefilah to procure water. Instead, he should clean his hands with stones, dirt, or other materials that cleanse.

 סצ"ב ס"ד ס"ק י"ג, ט"ו,כ וכ"א ביה"ל ד"ה צריך ביאורים ומוספים דרשו 24

Is one obligated to wash before davening if his hands are not dirty?

A person is also obligated to wash before davening even if he does not know that his hands are dirty. This concept is known as stam yadayim, and refers to a situation where one was not paying attention to the cleanliness of his hands. The concern is that since a person’s hands are always moving, they may have inadvertently touched an unclean area. For stam yadayim, one is only obligated to wash if there is water available. Otherwise, he should wipe his hands on a cleansing surface. If a person washed his hands before learning and was not paying attention to their cleanliness afterwards, he must wash again before davening.

ס"ה ס"ק כ"ג-כ"ה ביאורים ומוספים דרשו 29

What is the appropriate way to clean one’s hands when learning?

It is forbidden to touch an unclean part of the body or to scratch one’s head during davening or learning. Unclean areas include any part of the body which is normally covered as well as wax or mucus from the ears and nose. If a person touched an unclean area while learning, he should just wipe his hands on a cleansing surface. If this occurred during Kriyas Shema or while reciting any brochos, he must go and wash his hands. During Shemoneh Esrei, when it is forbidden to walk to a sink, wiping the hands is sufficient.

ס"ו וז' ס"ק כ"ז-כ"ט

• If one began to learn on his own before he needed the bathroom, he may complete the entire topic that he is studying if the need arises while he is learning. One certainly does not need to be stringent if stopping would cause him not to return to his learning.

• Rema rules that if one develops a strong need to relieve himself while davening -- to the extent that delaying will cause him to transgress the prohibition of bal tishaktzu -- he must stop and relieve himself. Other Achronim disagree and say that one should not stop in the middle of Shemoneh Esrei (provided that he had no need when he started) even if a very strong urge develops.

• If one is unable to complete Shemoneh Esrei due to his need to relieve himself, he must stop and leave the shul to attend to his needs. When he is done, it is unclear whether he must return to his place in shul to complete Shemoneh Esrei.

• May one collect tzedakah in middle of davening?

• What state of mind should one be in before he davens?

• How much time must one spend in preparation for davening?