Hold down button for in trigger

Hello everyone. I am trying to make a part in my game where you would walk up to a water hole and hold down “e” for 5 seconds and the water integer increases. I have been using a trigger to do this and it has worked so far, but i need to know how to hold the button down for 5 seconds, then it increases the variable. Here is my code (fairly simple)

Thank-You

	var playerObj : GameObject;	

	    


	
	
	function OnTriggerStay (other : Collider) 
	{
	
		
		if(Input.GetKeyDown("e"))
		{
		playerObj.GetComponent(GUISurvival_Icons).currentThirst += 10;
		}
		
		
	}

For the time, you can use delta time. Each intiger of 1 is 1 second in length. You can set an alarm when the trigger is entered and reset it to five when it’s left. Here’s how I use mine.

public var Alarm1 : float = -0.1;

function Update () {
        // Alarm1 activation. While the alarm is greater than zero, raise the water.
 	        if(Alarm1 > 0){
  			Alarm1 -= Time.deltaTime;
		}
        // If alarm1 runs out, personally, I prefer set it to -0.1 to keep it below zero. It should've be 5 seconds by here.
		if(Alarm1 < 0){
                        Alarm1 = -0.1;
                        //Water code.
                }
}

If the button is released, just reset the alarm to 5.

I hope this helps out and good luck with your project!