Place 1 diced ripe beefsteak tomato (about 10 ounces), 2 roughly-chopped stalks celery and 1 diced small red pepper in a pitcher. For still infused water, add 2 quarts of water. For sparkling water, add 1 quart of seltzer during prep and a second quart just before serving. Refrigerate 2 to 4 hours to allow the ingredients to infuse. Stir well and strain, discarding the solids. For serving, add fresh cut-up tomato, celery and pepper for garnish and plenty of ice. The infused water will keep refrigerated for up to 2 days.