Is it forbidden by the LEED to have à Infrared Taps / sensor taps/automatic Taps

No. It is not forbidden. I remember you could claim additional water saving in LEED v3 for sensor taps. That is no longer the case in LEED v4. The reference guide mentions research proving that they sensors do not help achieve additional saving. I find it counter intuitive and curious how is that possible. Sceptical of such research.

Hi Samuel,  Let me correct something. In v2009, you could take extra credit for METERED FAUCETS. These ARE NOT the infrared sensor type. These are faucets that have a timed cycle; the old-school kind where you push down on the top and they stay on for a pre-set number of seconds whether the user is still there or done and gone. You scored best for LEED by setting these for 12 seconds. This limited the amount of water used in each cycle and eliminated the problem of fools leaving the water on when they left the restroom.   HOWEVER people often just hit them for a 2nd cycle and walked away partway through. And as most commercial projects in the USA started to adopt infra-red sensors, it became clear that these were the better way to save water. But since there was no longer a pre-set time period, you could no longer make a calculation for reduced water use.  So you are right, not only does LEED not forbid infra-red fixtures, they are the reason the special metered faucet exception was ditched. At least, according to my sources.    

Thanks Susan. Now it makes a lot more sense. 

No, metered faucets are not forbidden; they just don't get you an advantage anymore.

Dear Sara, I know this might be confusing. I hope the following information helps you. This is taken from a communication with the GBCI back in 2017: ORIGINAL INQUIRY: It is cited on page 282 (Changes from LEED 2009) of the LEED Reference Guide for Building Design and Construction that: "Duration-based savings from autocontrol faucets with automatic fixture sensors or metering controls are no longer allowed in the design case. Studies have shown that autocontrol faucets do not save water because users frequently reactivate the faucet after initial use or stop washing before the cycle ends".
This is not found nor cited on the LEED Reference Guide for Interior Design and Construction, then: are autocontrol faucets with automatic fixture sensors or metering controls allowed or not allowed within LEED CI v4? GBCI Reply: Thank you for your query regarding Auto-control faucets. Autocontrol faucets with automatic fixture sensors or metering controls are not banned from usage in either LEED BD+C or LEED ID+C. However, duration based savings from these fixtures are no longer allowed in LEED v4, including ID+C projects. Several studies have shown that they do not save water since users can frequently reactivate the faucet after initial use or stop washing before the cycle ends. Please see Compliance Path 2. Usage-Based Calculation > Step 3. Complete Calculations of the Step-by-Step Guidance of the prerequisite. Equation 2 provides several different faucet flow rate conversions that may be used to convert gallons (liters) per cycle to a flow rate in gallons (liters) per minute.