Piscine Carletti (Acqua Santa), Italy

Getting to Piscine Carletti (Acqua Santa)

Piscine Carletti is reached from Viterbo by following the road eastward toward Tuscania along the Strada Tuscanese. Passing the entrance to the military air base, continue approximately one kilometre to find the thermal area on the left, signposted as Piscine Carletti or Sorgente Termale. The entrance is at the intersection of SP15 Strada Terme and the Strada Tuscanese, in locality Marinelle. The total distance from the centre of Viterbo is approximately 2.5 kilometres.

By car from Rome, take the A1 motorway north and exit at Orte, then follow the E45 superstrada toward Viterbo. Take the Viterbo Terme exit and continue toward Tuscania for approximately 3 kilometres. Turn left before the junction with Strada Bagni. Free parking is available directly beside the pools with no size or time restrictions; the area accommodates campervans and is used informally for overnight stays, though no hookups or services are provided.

By bus, Viterbo's urban bus network stops a few metres from the pools on Strada Terme. The nearest train station is Viterbo Porta Fiorentina, connected to Rome Ostiense by the Roma-Viterbo regional line. From the station, the city bus to Strada Terme provides direct access. Viterbo is within easy driving distance of Bagnaccio (8km), Bullicame (1km), and Terme dei Papi, making it practical to combine multiple free hot springs near Viterbo in one day.

Who Piscine Carletti Suits

Piscine Carletti suits visitors looking for an authentic, unmanaged natural hot spring experience without cost or facilities. The tiered basins create a natural temperature gradient allowing visitors to select a pool suited to their tolerance. The hottest basins near the source are popular in winter; the cooler lower basins are more used during warmer months. The site is a local favourite for after-dark soaking, as the pools are accessible 24 hours a day with no closing time and the steam rising from the water is particularly atmospheric at night.

Families can use the site, as the cooler downstream basins are comfortable for children at supervised and appropriate temperatures. Parents should keep young children away from the upper basins, where water temperatures are too high for safe immersion. There are no changing facilities, no toilets, and no shade. Visitors should bring towels, water, food, and everything needed for the session. Bathing attire is commonly worn but the site has no formal dress code as it is unmanaged.

Wheelchair access is not possible at this site. The terrain is uneven and natural, with muddy paths between basins, gravel parking, and no paved routes. Visitors with mobility limitations should consider the managed alternatives nearby: Bagnaccio at 8km has changing cabins and a more organised layout, and Terme dei Papi is a fully managed facility approximately 2km away. For those specifically seeking free hot springs in Italy with a more rustic setting, Carletti is among the most accessible free springs in Lazio by public bus.

Piscine Carletti (Acqua Santa) Safety Tips

Piscine Carletti is an unmanaged site with no staff, no lifeguard, and no emergency equipment on site. The upper basins receive water directly from the source at approximately 58 degrees Celsius, which is well above safe bathing temperature. Never enter the first or second basin without testing the temperature carefully and never immerse the head or face in the hottest pools. Acclimatise by entering the cooler downstream basins first before moving toward the hotter upper pools.

The water is classified as sulphureous and contains dissolved hydrogen sulphide, which produces a sulphur odour. This is a natural feature of the spring and is part of its traditional therapeutic profile. Individuals with respiratory conditions, sulphur sensitivity, or cardiovascular disorders should consult a doctor before bathing. Pregnant women should avoid prolonged immersion in high-temperature basins. Keep soaking sessions short, particularly in the hotter pools; 10 to 15 minutes per basin is the commonly cited guideline.

The site is open 24 hours but has no lighting. Bring a torch for evening visits. In summer the lawn has no shade; the combination of sun and hot water can cause overheating quickly. Bring plenty of drinking water and avoid the hottest midday hours in July and August. Basin mud can stain swimwear.

No bins or toilets are on site. Carry out all waste. Dogs may accompany visitors on the grass but not in the water. The site can be crowded on summer weekends; arriving early or in the evening avoids the busiest times. A bar and trattoria is approximately 250 metres away on Strada Terme.