Introduction

The subject of aromatic waters is intriguing, yet not one on which very much has been written. It has been necessary to search many books on herbalism and aromatherapy to glean snippets of information. Even then the quality of information is not always very good, and very little would stand up to rigorous examination (save for the information on kekik water (Aydin, Baser & Öztürk 1996)). Most has been found in the French literature, as France is the country that most uses hydrolats, although even there not to a great extent today.

Water has the remarkable capability of picking up information relating to the vibrational energy found in a living plant, of storing this information and, under certain circumstances, of transferring it to the human body. This means that distilled hydrolats pick up and store not only physical plant particles (Roulier 1990) but possibly also subtle energetic information; consequently, such products have an almost homoeopathic aspect.

There are several kinds of water-based aromatic product used in therapies, including infusions, teas (it has been estimated that over 1 000 000 cups of chamomile tea are taken every day worldwide (Foster 1996)), tisanes, wines, vinegars and aromatic waters, which may be distilled or prepared. Distilled aromatic waters – hydrolats – contain the water-soluble compounds of the plant, but not the tannic acid and bitter substances, and make an excellent complement to that other product of distillation, the powerful essential oils. They are, however, very different in nature from the volatile essential oils, albeit obtained from the same plant, in as much as they are without aggression and are active on a different level; these ‘gentle giants’ are subtle, safe and effective, although any treatment must be carried out over a longer period of time than when using essential oils.

Some plants, whether containing essential oils or not, are distilled specifically for the hydrolat and not for the essential oil; when plants are distilled specifically for the hydrolat the quality of the water used is of great importance. Although there may be no volatile or aromatic molecules in these plants, and hence no aromatic oil, all water-soluble molecules within the plant are taken up by the steam; thus the hydrolats stand intermediate between, and to some extent represent a fusion of, aromatherapy and herbalism, containing as they do some of the useful plant molecules from both worlds. Hydrolats are used in conjunction with both essential oil treatments and herbalism, as well as on their own.

As these valuable products of the distillation process are so safe in use, they deserve to be much better known and far more widely used, especially by aromatherapists already familiar with the essential oils. Hydrolats last featured in the French Codex in 1965.

Terminology

In France the term hydrolat is used to describe the condensed steam which has passed through the plant material; the translation of hydrolat is given as ‘aromatic, medicated water’ (Mansion 1971) and this is the nomenclature adopted by Price and Price (2004 p. 31–34) to describe distilled plant waters, but many names are in use, some more accurate than others.

Terms used for these products are:

Prepared aromatic waters

These are not produced by the distillation process but are put together in a laboratory. They consist of distilled water with the addition of one or more essential oils; these oils may be genuine plant extracts (volatile oil, absolute or concrete) or they may be partly or wholly artificial or synthetic. Essential oils are not generally soluble in water – probably on average only about 20% of any given oil is water soluble – but many can be ‘knocked’ into solution by shaking to produce a saturated solution. For each litre of distilled water 2–3 g (40–60 drops) of essential oil can be added; this must be shaken frequently and vigorously for 2 or 3 days and then stored in a cool place; it can be stored successfully at 10–15°C for several months. Essential oils suitable for use by this method are anise, basil, Borneo camphor, caraway, chamomile, cinnamon, citron, coriander, cypress, eucalyptus, fennel, garlic, geranium, hyssop, juniper, lavender, lemon, marjoram, melissa, niaouli, nutmeg, orange, origanum, peppermint, rosemary, sage, savory, tangerine, tarragon, verbena and ylang ylang (Lautié & Passebecq 1979 p. 91).

Prepared waters may be used for gargles, mouthwashes, bathing wounds and for ingestion, where 20 mL of the made water contains one drop of essential oil and therefore one teaspoonful contains about a quarter of a drop (about 0.25% concentration). Many essential oils exhibit significant bactericidal power at a concentration of 0.25%, as found in prepared waters, e.g. in a concentration of 0.18% clove essential oil kills the tubercle bacillus in a few minutes without causing any tissue damage or risk of toxicity, in contrast to some other preparations and antibiotics (Lautié & Passebecq 1979 p. 92).

Prepared waters do not have the same make-up as essential (distilled) waters, and therefore cannot have the same therapeutic properties. Some prepared waters are made with alcohol, and these are not recommended for use alongside aromatherapy. The main volume of sales of prepared waters is to skincare manufacturers for use in ‘natural’ skin toners, refreshers and washes. Water which has had essential oil(s), synthetics or alcohol added to it is not a hydrolat, and the two should not be confused. To achieve a genuine plant water, distillation alone is the true method.

What are hydrolats?

Hydrolats are a product of distillation and can be considered as true partial extracts of the plant material from which they are derived. They may be byproducts of the distillation of volatile oils, e.g. chamomile water and lavender water, or of the distillation of plant material which has no volatile oil, e.g. elderflower, cornflower, plantain. Their method of preparation, by definition, necessitates that they be totally natural products with no added synthetic fragrance components. Hydrolats are obtained from aromatic and other plants by steam distillation, and during this process a proportion of the water-soluble compounds of the essential oil contained in the plant matter is absorbed by and retained in the water. As some essential oils have a relatively high proportion of water-soluble compounds, much of the essential oil can be lost to the water during the distillation process, e.g. Melissa officinalis [lemon balm]; in such cases it is imperative to use cohobation. This is a system whereby the water/steam in contact with the biomass during distillation is continuously recirculated, giving maximal opportunity for the water-soluble elements of the essential oil and the plant to pass into the water. Eventually this water reaches saturation point, when no more of the essential oil components can pass into solution (it is at this stage that the complete essential oil is gained); thus a water is produced that is rich not only in some essential oil molecules but also in other hydrophilic molecules found in the plant which are not usually part of the essential oil. When distilling for hydrolats, it is important that the water used in the distillation process should be of good quality, preferably from a non-polluted spring, and free of any chemical cleansers that may have been used to clean the still.

Aromatic waters contain about 0.02–0.05% (or perhaps more, depending on the plant) of the water-soluble parts of the essential oil freely dispersed in an ionized form; this is equivalent to up to approximately 10 drops per litre of hydrolat (Price & Price 2004 p. 47). They may have similar properties to the parent oils but not to the same degree, and often their properties are different.

Which plants yield a hydrolat?

Many aromatherapists think that only plants containing an essential oil are distilled, but this is not so. Many plants containing very little or no essential oil at all are processed, primarily to gain the hydrolat. The hydrolat from each plant, like the essential oil, is unique and reacts according to its constituents. Hypericum perforatum, often macerated in olive oil to obtain its therapeutic properties (see Carrier oils in Ch. 8), is an example of a plant that contains an essential oil but which is rarely distilled for this on account of the minute yield, which would cause the price to be prohibitive; it is therefore distilled for its hydrolat. Plantago lanceolata [plantain] is an example of a non-aromatic plant which is distilled only for its hydrolat. This illustrates that water-soluble molecules other than volatile essential oil molecules can be taken into the steam, yielding a therapeutic water at the end of the process.

Yield

It is not possible to obtain an almost unlimited or even a large quantity of water from a small amount of plant material. The quantity of hydrolat is proportionately limited to the plant weight, and therefore hydrolats of excellent quality are obtained when cohobation is an integral part of the distilling process. This method is used to produce a number of hydrolats, e.g. rose, and yields a saturated hydrolat; Melissa is another case where a whole essential oil cannot be achieved until the steam water is saturated with the water-soluble molecules of the essential oil, thereby preventing the loss of these from the essential oil.

Yields of distilled waters usually lie between the limits of 1–1.5 and 2–5 L/kg of plant matter, and vary according to the particular plant. The waters of thyme, savory and rosemary require a smaller quantity of plant than do waters of lettuce, hawthorn, yarrow or hemp agrimony. Some waters are known as ‘weight for weight’ products, as the quantities of plant matter and water product are equal, e.g. 100 lb of roses are distilled with sufficient water to yield 100 lb of fragrant rose water (Poucher 1936).