To answer your questions:
1. No - You cannot deduct the water you drink on the job.
2. Yes - If the shoes are specialty shoes and ONLY used when detailing, If you can wear them at other times (regardless of whether you do or not), they are not considered special equipment and you cannot deduct them.
3. Yes - you can deduct the business portion of your cell phone and WiFi bills.
4. Your prescription medicine and medical bills are deductible on your 1040 return. Please keep in mind the following about deducting your medical expenses:
- You don't get the benefit if you are taking the standard deduction.
- If you itemize deductions, you will only be able to take total medical expenses that are greater than 7.5% of your adjusted gross income
