Washing the hands after leaving a cemetery:
One who walks amongst graves [i.e. cemetery] is required to wash his hands [immediately] afterwards [being that the evil spirits escorts the person until he washes]. Although from the letter of the law washing one time suffices, the custom is to wash ones hands three times inconsecutively after leaving a cemetery. 
May one wash his hands in the cemetery? One is to wash the hands only after distancing himself four Amos from the cemetery.
Is one to wash his hands prior to entering into a house? Yes.
Must one wash his hands after leaving the burial grounds of Tzaddikim? The custom is not to wash hands after leaving the resting place of a Tzaddik unless the Tzaddik is buried in a cemetery or near other graves.
Wash the face after leaving a cemetery:
Throwing grass or earth behind the back after leaving a cemetery:
Some are accustomed to do so after leaving a cemetery. [The Rebbe’s custom: Prior to leaving the Ohel the Rebbe would tear grass from the ground three times and throw it behind him.]
 Between the graves is explained to refer to a cemetery. [M”A 4/20 in name of Teshuvos Mahril 23; Kol Bo; Chayeh Adam 2/5; Kitzur SH”A 2/9; M”B 4/42; Gesher Hachaim 16/8; Kaf Hachaim 4/76; Piskeiy Teshuvos 4/25]
Opinion of Admur: The Rama 4/18 writes “one who walks between the dead.” The M”A records that this means a cemetery. Admur does not record either the wording of the M”A or the Rama rather he writes “between the graves”. Vetzaruch Iyun if there is any practical ramification between the graves or a cemetery.
 Rav Asher Lemel HaKohen, Rav of Anash Beitar, related to me that one time his father, the renowned Posek Rav Avraham Hirsh Hakohen approached the sink to wash his hands on the upper floor of 770. He then noticed the Rebbe behind him and quickly let him through to wash hands first. After washing hands the Rebbe told him that he needed to “cut the line” as he was by the cemetery [of his father in-law] and did not want to delay the removal of impurity. Seemingly, at that time, there was no place to wash hands at the actual cemetery.
 M”A 4/20 in name of Teshuvos Mahril; this applies according to all. See Halacha 2 in footnotes.
 Elya Raba 4/12; Machatzis Hashekel 4/17; Soles Belula 4/14; Machazik Bracha 4/6 in name of Makor Chaim; Ben Ish Chaiy Toldos 16; Kaf Hachaim 4/61; M”B 4/39; Ketzos Hashulchan 2 footnote 29 regarding Levaya; Olas Tamid; Shlah Shaar Haosiyos 9; Lev Chaim 1/63; Kaf Hachaim [Falagi] 7/26; Ruach Chaim 4/3; Chesed Lealafim brought in Kaf Hachaim 4/61; Piskeiy Teshuvos 4/25 footnote 241 Rabbi Leibal Groner related to me that the Rebbe would wash his hands three times and then turn over the washing basin.
Kama 4/18; M”A 4/17; Seder Hayom; Kneses Hagedola all rule that one is not required to wash three times. Nevertheless the custom today has become to follow the opinions brought above.
 M”A 4/20 in name of Teshuvos Mahril; M”B 4/42
 See Piskeiy Teshuvos 4/25 footnote 247
 Gesher Hachaim 16/8
 Rama 376/4; Ishkavta Direbbe p. 107 learns this applies even when leaving a cemetery and so seems from Chochmas Adam 158/29, Vetzaruch Iyun from Piskeiy Teshuvos 4 footnote 244
 Ishkavta Dirrebe p. 106; Beis Rebbe “Harav Hakadosh Miberditchiv”; Piskeiy Teshuvos 4/25
The Alter Rebbe visited the resting place of Reb Levi Yitzchak of Berditchiv after he passed away. After Admur left the grave he was offered water to wash his hands and Admur replied that he does not need to wash his hands as the gravesite of Tzaddikim do not impurify.” [Beis Rebbe ibid] Practically this is the custom of the Chassidim not to wash hands after leaving the resting site of the Rabbeim, as was seen amongst Chasidim that visited the burial grounds of the Rebbe Maharash and Tzemach Tzedek [which are positioned in the entrance to the cemetery in Lubavitch]. Likewise the Rebbe Rashab would not wash hands after visiting the gravesite of his father the Rebbe Maharash. The reason for this is because although even the grave of a Tzaddik gives off impurity it nevertheless is a holy place and does not give off the evil spirit, and the entire purpose of washing the hands is to remove the evil spirit. [Ishkavta Direbbe ibid]
 Thus those that visit the Rebbe’s Ohel in Queens must wash hands afterwards being that it is within a cemetery. This was also the Rebbe’s custom. [Ishkavta Direbbe ibid]
 M”A 4/20 in name of Teshuvos Mahril; M”B 4/42 in name of Artzos Chaim
 Darkei Moshe 376/7
 Gesher Hachaim 16/9
 Hiskashrus 884