Shiva Purana
असंभवे तु द्रव्याणां यथासंभवसंभृतैः ॥ केवलैर्मंत्रतोयैर्वा स्नापयेच्छ्रद्धया शिवम् ॥ ४५ ॥
If the materials are not available whatever is available shall be used. Mere water with chantings of mantra can also be used for the ablution of Śiva. The devotee shall faithfully perform the rite.
english translation
asaMbhave tu dravyANAM yathAsaMbhavasaMbhRtaiH ॥ kevalairmaMtratoyairvA snApayecchraddhayA zivam ॥ 45 ॥
hk transliteration by Sanscript