A collection of ideas, suggestions and solutions for the planning, building and environment of private pools (for exclusive use with single family homes) and commercial (that is, pools located in condominiums, farm stays, wellness or fitness centers, natatorium facilities, etc.). Welcome to Italian Pool Design, a series of books that each year surprise our readers with the quality and quantity of images and technical drawings complimented by a descriptive text that can inspire all professionals operating in the sector of pools. In fact, each realization is accompanied by a technical profile of the particularities, multiple contents, pool dimensions, materials used for lining, recirculation, filtration, treatment, heating and accessories, and in some cases the overall cost of the project. This fourth volume, in particular, offers something new: the section dedicated to the biological and natural pools, that use alternative systems for water treatment, for example phyto - depuration by aquatic plants. It's important to note that every year this prestigious book coincides with the candidates participating in the Italian Pool Award, given by the technical magazine Piscine Oggi: reference point for the pool sector for more than 40 years. Italian Pool Design 4 in fact selects pools nominated in the 2013 edition for the Italian Pool Award. The winners of the award- in the category of outdoor geometric form, outdoor freeform, private indoor, commercial outdoor, commercial indoor, biological pool, Special Facebook award- are awarded at ForumPiscine, the annual Italian pool fair that every February invites the pool and wellness sector to Bologna's Fair. At this event the winners are made known with the Italian Pool Award logo. The book like the award and ForumPiscine event are realized for the same purpose: to show the world the masterwork of Italian design excellence in the realization of pools.